Logitech C270 HD webcam — 720p USB camera with built-in mic and automatic light correction. Solid pick for video calls, remote work, or basic streaming. This is the Logitech C270 HD Webcam, a budget plug-and-play USB camera suited for everyday video calls. It doesn’t strive for professional streaming quality, but it reliably handles meeting needs, student calls, or backup cam duties. Key Features & Functionality Records video in HD 720p at 30 fps Fixed focus lens (no autofocus) Built-in mono microphone with noise reduction (captures voice clearly in standard environments) Automatic light correction (RightLight / similar tech) to adjust in low or uneven lighting Universal mounting clip: works on laptop lids, monitors, or can sit on a shelf USB 2.0 interface, 1.5 m (≈ 5 ft) cable length Technical Specifications Strengths & Limitations Pros: Reliable and easy to set up: plug and play Good for video calls in decent lighting Noise suppression in mic helps reduce background hiss Affordable alternative if your built-in camera fails Cons: Only 720p — not ideal for high quality streaming Fixed focus — manual adjusting can’t zoom/focus No privacy shutter (you may need stickers or external cover) Color and sharpness aren’t top tier under weak light
Logitech G403 HERO – Ergonomic wired gaming mouse with HERO 25K sensor and ultra-precise 25,600 DPI tracking.Delivers pro-grade performance with customizable RGB, 6 buttons, and optional weight tuning. ✅ Full Specifications: Model: Logitech G403 HERO Sensor: HERO 25K Optical Sensor DPI: 100 – 25,600 DPI (adjustable with no smoothing, acceleration, or filtering) Polling Rate: 1000 Hz (1ms response time) Tracking Speed: >400 IPS Acceleration: >40G Buttons: 6 programmable buttons (including 2 side buttons) Switches: Mechanical with metal spring button tensioning (rated for 20M+ clicks) Lighting: RGB Lighting (logo and scroll wheel, customizable via G HUB) Weight: Approx. 87g (mouse only) + 10g optional weight Grip Style: Palm and claw grip support Cable: 2.1 meters (standard rubber cable) Build: Ergonomic right-handed design with rubber side grips Software: Logitech G HUB (for DPI, lighting, macros, and profiles) Compatibility: Windows 7 or later, macOS 10.11 or later, Chrome OS Onboard Memory: Yes (save DPI and button settings directly to the mouse)
A durable and versatile pre-owned Lenovo ThinkPad T470 with 14" touchscreen, 6th Gen Core i5, 8GB RAM, and 256GB SSD—ideal for professionals who need reliability, touch functionality, and trusted ThinkPad performance.
In the realm of monitors, the ViewSonic VA2201-H stands out as a reliable and clear solution, offering a perfect blend of visual excellence and simplicity for an enhanced viewing experience. Transitioning to its key features, the VA2201-H excels in providing crystal-clear visuals. This monitor is designed to deliver sharp and vibrant images, ensuring a visually engaging experience for work or entertainment. Moreover, this display impresses with its sleek and minimalistic design. The ViewSonic VA2201-H not only enhances the aesthetics of your workspace but also ensures straightforward setup, making it an ideal choice for users seeking simplicity. In addition to its functionality, the VA2201-H offers user-friendly controls and connectivity options, ensuring a hassle-free experience. This monitor seamlessly adapts to various settings, providing flexibility for different viewing preferences. Furthermore, ViewSonic’s commitment to user satisfaction is evident in the VA2201-H’s energy-efficient design and eye-care technology. It’s a reliable companion for extended viewing periods without compromising on visual quality. In conclusion, the ViewSonic VA2201-H redefines clarity and simplicity, combining clear visuals, sleek design, and user-friendly features. Elevate your viewing experience effortlessly with the VA2201-H – your clear and straightforward solution for visual excellence! Specifications Full HD 1080p 100Hz Refresh Rate 1ms Response Time Flicker-Free & Blue Light Filter View Mode: Game/Movie/Web/Text/Mono Inputs : HDMI/VGA Check other options here!
Are you ready to take your gaming to the next level? Dive into the realm of ViewSonic VX2758A-2K-PRO-2 gaming monitors, where affordability meets exceptional performance for an unmatched gaming experience. Firstly, enjoy crystal-clear visuals with ViewSonic’s high-resolution displays. Immerse yourself in the action with vibrant colors and sharp images, providing a gaming experience like never before. Transition smoothly between scenes with ViewSonic’s quick response times. Say goodbye to lag and motion blur, ensuring you stay ahead in the game and never miss a critical moment. Explore a range of sizes to suit your gaming setup. From compact options for cozy spaces to larger displays for a cinematic experience, ViewSonic has a gaming monitor to fit your preferences. Achieve optimal comfort with customizable settings. ViewSonic VX2758A-2K-PRO-2 gaming monitors offer adjustable brightness, contrast, and color settings, allowing you to tailor the display to your liking and reduce eye strain during extended gaming sessions. In conclusion, elevate your gaming setup without breaking the bank. ViewSonic VX2758A-2K-PRO-2 gaming monitors provide the perfect blend of affordability and top-notch performance, delivering a visually stunning and responsive gaming journey. Level up your gaming experience with ViewSonic today! Specifications: Resolution : 2K QHD Display : 27″ IPS Refresh Rate : 170Hz Response Time : 1ms
The Samsung 75″ QLED 4K Q60F Smart TV QA75Q6FAAUXTW delivers a large-screen entertainment experience with advanced QLED display technology. It produces bright colors, sharp details, and impressive clarity, making movies, sports, and games more enjoyable on the expansive 75-inch screen. QLED technology uses Quantum Dot enhancement to improve color accuracy and brightness. As a result, images appear vivid and lifelike across a wide range of content. Dark scenes retain detail, while bright scenes remain balanced and clear. This helps create a consistent viewing experience throughout the day. The 4K UHD resolution provides four times the detail of Full HD content. Therefore, images look sharper and more refined. In addition, Samsung’s processing technology enhances lower-resolution content, helping it appear clearer and closer to 4K quality. HDR support improves contrast and expands the range of visible colors. This allows brighter highlights and deeper shadows, creating a more realistic picture. Fast-moving scenes also appear smoother, making sports broadcasts and action movies more enjoyable to watch. The Smart TV platform offers convenient access to popular streaming services, apps, and connected home features. It responds quickly and provides an easy-to-use interface for everyday entertainment. In addition, the slim design and narrow bezels give the Samsung QLED 75 4K Q60F Smart TV QA75Q6FAAUXTW a modern appearance that complements a variety of living spaces. Overall, this Samsung QLED TV combines large-screen immersion, vibrant color performance, and smart connectivity for a reliable home entertainment solution. Specifications: QLED technology delivers vibrant colors and enhanced brightness 75-inch 4K UHD display provides immersive viewing HDR improves contrast and image realism Smart TV platform supports streaming apps and connected features Slim design complements modern living spaces
The Philips 27″ 100Hz LCD Monitor is the perfect choice for work, entertainment, and gaming. It delivers smooth visuals with a high refresh rate, ensuring a seamless viewing experience. With a 100Hz refresh rate, this monitor provides fluid motion, reducing screen tearing and stuttering. Whether you’re watching videos or playing games, you can enjoy clear and sharp visuals. The Full HD resolution ensures crisp details and vibrant colors for an immersive experience. The Philips 27″ 100Hz LCD Monitor features an ultra-slim design that enhances your workspace. Its narrow bezels provide a sleek, modern look, making it perfect for multi-monitor setups. The adjustable stand allows you to find the most comfortable viewing position. Setting up this monitor is easy with multiple connectivity options, including HDMI and VGA ports. It’s compatible with laptops, desktops, and gaming consoles, offering flexibility for different devices. Eye strain is reduced thanks to Philips’ Flicker-Free technology and LowBlue Mode. These features provide a more comfortable viewing experience, especially during long hours of use. Whether you’re working or gaming, your eyes will feel less fatigued. Energy efficiency is another key benefit of the Philips 27″ LCD Monitor. It consumes less power while delivering high performance, making it an eco-friendly choice for your home or office. Upgrade your display today and enjoy smoother visuals, vibrant colors, and ergonomic comfort. The Philips 27″ 100Hz LCD Monitor is a great addition to any setup. Specifications: Display : 27″ VA Resolution : 1920 x 1080 FHD Refresh Rate : 100Hz Response Rate : 4ms
A1707 Battery Replacement, A1820 Battery for MacBook Pro 15″ (Late 2016, Mid 2017) Touch Bar EMC 3072 EMC 3162 MLH32 MLH42 MLW72 MLW82 MPTR2 MPTT2 MLH52 MLW92 MPTU2 MPTV2 MPTW2 MPTX2 Specification】Voltage: 11.4V. Capacity: 76Wh 6667mAh. Battery Type: Li-ion. Condition: Brand new, from high quality materials, top circuit boards and smart chip. 【Compatible Part Number】A1820, A1707, A1707(EMC 3072), A1707(EMC 3162), 020-01728, MacBookPro13,3 , MacBookPro14,3. 【Compatible Laptop Models】MacBook Pro 15-Inch (Late 2016) & (Mid 2017) Model A1707 with touch bar, fit for MLH32LL/A MLH42LL/A MLH52LL/A MLW92LL/A MPTU2LL/A MPTV2LL/A MPTR2LL/A MPTT2LL/A MPTW2LL/A MPTX2LL/A MLW72LL/A MLW82LL/A. 【Note】The tools are included. Double-sided tape is attached to the back of the battery or double-sided tape is included in the package. But No battery installation instruction. The MBP battery is difficult to disassemble, we suggest you search for related installation videos on the Internet or find a technician for help.
The MSI MAG 256F 24.5″ 180Hz Gaming Monitor is crafted for serious gamers. With a fast 24.5-inch Full HD display, this monitor delivers exceptional clarity and performance. Its 180Hz refresh rate and 1ms response time ensure smooth, blur-free visuals, making it perfect for fast-paced games. Gamers will appreciate the 180Hz refresh rate of this monitor. It minimizes screen tearing and ghosting, providing a seamless experience in every frame. This high refresh rate, combined with a 1ms response time, means you’ll experience gaming with precision and speed. The Full HD resolution ensures sharp, clear images, bringing your games to life. This monitor also supports Adaptive Sync technology. It helps synchronize the monitor’s refresh rate with your graphics card, reducing stuttering and screen tearing. This feature is especially valuable for competitive gaming, where every millisecond counts. The design of the MSI MAG 256F 24.5″ 180Hz Gaming Monitor is sleek and gamer-friendly. It has a frameless design that maximizes screen space, allowing for immersive gaming. Its adjustable stand lets you customize the height and tilt for comfortable viewing angles, reducing neck strain during extended gaming sessions. This monitor also features multiple connectivity options, including HDMI and DisplayPort. This makes it easy to connect your gaming console or PC, giving you flexibility with your setup. Its easy navigation OSD (on-screen display) allows you to make quick adjustments to the settings. Upgrade your gaming experience with the MSI MAG 256F 24.5″ 180Hz Gaming Monitor. Enjoy fluid, responsive gameplay and impressive visuals with this reliable and stylish monitor. Specifications: Display : 24.5″ Rapid IPS Resolution : FHD (1920 x 1080) Refresh Rate : 180Hz Response Rate : 1ms GTG
BenQ RE03A 86 inch Board Essential RE8603A is designed for classrooms, training rooms, and interactive presentations. It features an 86-inch 4K UHD IPS display with precision IR touch technology for smooth writing and collaboration. Additionally, it supports up to 40 touch points. Therefore, it helps teachers and teams work together more efficiently. The BenQ RE8603A delivers 3840 × 2160 resolution with 450 nits brightness and anti-glare coating for clear viewing in bright rooms. Moreover, it uses 9H tempered glass for better durability and safer daily use. It also includes low blue light and flicker-free technology to reduce eye strain. In addition, it runs on Android 11 with 4GB memory and 32GB storage for smooth system performance. Furthermore, it provides 3 HDMI 2.0 ports, DisplayPort, USB-A, USB-C, and USB-B for flexible connectivity. As a result, users can connect laptops, cameras, and classroom devices easily. It also includes front-facing 2 × 20W speakers and built-in management tools for daily educational use. Specifications: 86-inch 4K UHD (3840 × 2160) IPS display Precision IR touch with up to 40 touch points Android 11 with 4GB RAM and 32GB storage 450 nits brightness with anti-glare 9H tempered glass 3 HDMI 2.0, DisplayPort, USB-C, and dual 20W speakers
BenQ RE6504 65” 4K UHD Interactive Flat Panel with Android 13 is a large interactive display designed for classrooms, meeting rooms, and training environments. It combines a 4K touchscreen, built-in Android system, and collaboration tools for interactive presentations. It features a 65-inch IPS panel with 3840 × 2160 (4K UHD) resolution. Therefore, it delivers sharp visuals and wide viewing angles for group interaction. In addition, it supports up to 40-point touch input for multi-user collaboration and writing. Moreover, the panel runs Android (EDLA certified, Android 14/13 depending on region) with built-in apps and Google services support. As a result, users can install apps, browse content, and run teaching or presentation tools directly on the display without an external PC. The RE6504 uses precision IR touch technology. Therefore, it provides fast and accurate writing with low delay. In addition, it includes anti-glare and tempered 9H glass for durability and better visibility in bright rooms. Furthermore, it includes multiple connectivity options such as HDMI, USB, USB-C, OPS slot, and LAN. As a result, it supports laptops, media players, and modular PC systems for flexible installation. It also includes built-in speakers and collaboration software tools. Therefore, it supports presentations, whiteboarding, screen sharing, and remote teaching or meeting scenarios. Finally, the BenQ RE6504 delivers a large 4K interactive workspace with Android integration, multi-touch control, and strong connectivity for education and business use. Specifications: Display: 65-inch IPS panel with 3840×2160 4K UHD resolution Touch: Up to 40-point multi-touch for collaboration System: Built-in Android (EDLA support with Google services) Glass: Anti-glare 9H tempered glass for durability Connectivity: HDMI, USB, USB-C, OPS slot, and LAN support
This item is available on backorder from abroad. A 50% down payment should be transferred to confirm the order and our salesman will specify the time till arrival after confirmation. The BenQ ZOWIE XL2586X 24″ 540Hz Gaming Monitor is designed for serious gamers. It delivers ultra-smooth visuals, ensuring you never miss a moment in fast-paced games. Firstly with a 540Hz refresh rate, the BenQ ZOWIE provides incredibly smooth gameplay. This high refresh rate reduces motion blur and offers a competitive edge in gaming. Furthermore the monitor features a 24-inch screen, offering a perfect balance between size and performance. It ensures you get an immersive gaming experience without overwhelming your desk space. Moreover the BenQ ZOWIE is equipped with a fast response time. This feature ensures that your actions are reflected on-screen instantly, providing a seamless gaming experience. Also enjoy vibrant and accurate colors with the BenQ ZOWIE XL2586X’s advanced color settings. This monitor allows you to customize your display settings to match your preferences and game requirements. The ergonomic design of the BenQ ZOWIE allows for height, tilt, and swivel adjustments. This ensures you can play comfortably for extended periods, reducing strain and enhancing your focus. The BenQ ZOWIE also includes features like Black eQualizer and Color Vibrance. These features enhance visibility in dark scenes and adjust color settings to your liking. In conclusion, the BenQ ZOWIE XL2586X 24″ 540Hz Gaming Monitor is a top choice for gamers seeking superior performance. Upgrade your gaming setup with the XL2586X and experience the next level of competitive gaming. Specifications: Display : 24.1″ Fast TN Resolution : 1920 x 1080 Refresh Rate : 540Hz
The Lexar NS100 512GB SSD is a 2.5-inch SATA III solid-state drive built to upgrade laptops and desktops with faster boot times, smoother app loading, and silent operation. It uses reliable flash storage to deliver a clear performance boost over traditional hard drives. ⚡ Faster System Performance: Significantly improves boot speed, application loading, and file transfers versus HDDs. 💾 512GB Storage Capacity: Ideal for OS, software, documents, and everyday multimedia. 🧠 SATA III 6Gb/s Interface: Provides stable, high-speed performance and is backward compatible with SATA II/I systems. 🔇 Silent & Shock-Resistant: No moving parts, making it quieter and more durable for laptops and mobile use. 🌡️ Low Power Consumption: Helps reduce heat and extend laptop battery life. 🛠️ Easy Installation: Standard 2.5″ 7mm design fits most laptops and desktops.
A premium ultralight pre-owned Lenovo ThinkPad T14s Gen 2 with 14" display, 11th Gen Core i5, 16GB RAM, and 512GB SSD—delivering powerful performance, all-day battery life, and exceptional portability for professionals on the move.
The MSI MAG 27CQ6F 27″ is a high-performance gaming monitor made for smooth and sharp visuals. It features a 27-inch curved display that enhances your viewing experience. With a 170Hz refresh rate, the MSI MAG 27CQ6F 27 delivers ultra-smooth action in every game. In addition, the 1ms response time ensures fast and clear visuals with no motion blur. This makes it ideal for fast-paced gaming. Moreover, the MSI MAG 27CQ6F 27″ uses a QHD resolution for crisp and detailed images. Thanks to its VA panel technology, colors appear rich and vibrant from all angles. Plus, the MSI MAG 27CQ6F 27 includes anti-flicker and low blue light features for better eye comfort. You can enjoy long hours of gaming without strain. The design of the MSI MAG 27CQ6F 27″ is sleek and modern, fitting perfectly into any setup. It supports tilt adjustment, so you can find the most comfortable viewing angle. Furthermore, its curved screen brings you closer to the action. For smoother gameplay, the MSI MAG 27CQ6F 27 “includes FreeSync support, reducing screen tearing and stuttering. You get a clear and stable picture every time you play. Also, the monitor has multiple ports for easy device connection. Whether you game, stream, or work, the MSI MAG 27CQ6F 27” offers reliable performance. Its fast response, great colors, and smart design make it a great choice. You’ll enjoy every detail and every moment on this monitor. To sum up, the MSI MAG 27CQ6F 27″ is perfect for gamers who want speed, clarity, and comfort in one screen. Specifications: Display : 27″ Rapid VA Resolution : 2560 x 1440 (WQHD) Refresh Rate : 180Hz Response Time : 0.5ms (GtG, Min.) Curvature : Curve 1500R
Looking for a top-notch monitor to enhance your computing experience? The MSI Pro MP275Q 27″ 100Hz Monitor is the perfect choice. This monitor offers superior performance and stunning visuals, making it ideal for both work and play. Firstly, the 27-inch screen provides ample space for multitasking. Whether you’re working on multiple documents or enjoying a movie, the large display ensures you have all the room you need. The Full HD resolution delivers sharp and clear images, enhancing every detail. The 100Hz refresh rate is a standout feature of this monitor. It provides smooth and fluid visuals, which is particularly beneficial for gaming and video playback. You won’t experience any stuttering or lag, ensuring a seamless viewing experience. Another advantage of the MSI Pro MP275Q is its wide color gamut. This feature ensures vibrant and accurate colors, making it perfect for tasks that require color precision, such as photo editing or graphic design. Your projects will look exactly as you intend them to. Moreover, the monitor includes advanced eye care technology. It reduces blue light emission and flicker, helping to minimize eye strain during long periods of use. This makes it an excellent choice for professionals who spend hours in front of their screens. Connectivity is also a breeze with the MSI Pro MP275Q. It features multiple input options, including HDMI and DisplayPort, allowing you to connect various devices effortlessly. This flexibility ensures compatibility with your existing setup. In conclusion, the MSI Pro MP275Q 27″ 100Hz Monitor offers a superior viewing experience with its large screen, high refresh rate, vibrant colors, and eye care technology. Upgrade your setup today and enjoy enhanced performance and stunning visuals. Specifications: Display : 27″ IPS Resolution : 2560 x 1440 (WQHD) Refresh Rate : 100Hz Response Rate : 1ms MRPT
The Xiaomi TV A Pro 55 2026 delivers sharp and vibrant visuals for movies, shows, and games. Its 55-inch QLED 4K display provides detailed, lifelike images with bright colors and deep contrast. High resolution ensures that every scene shows fine details clearly. The TV uses a quantum-dot QLED panel that enhances color accuracy and expands the color range. Colors appear vivid, realistic, and consistent from scene to scene. Dark areas stay deep, bright areas stay clear, and overall image quality feels more natural and immersive. The Xiaomi TV A Pro 55 2026 also supports advanced HDR formats like HDR10+ and HLG. These boost contrast and improve brightness and shadow detail, resulting in richer and more cinematic picture quality. An additional HDR enhancement mode further refines overall image depth and clarity. Sound quality is enhanced with built-in dual speakers supporting Dolby Audio and DTS:X. This provides clear, balanced, and immersive audio without requiring external speakers. Design-wise, the TV features a premium metal frame with ultra-slim bezels, giving it a sleek and modern appearance that fits well into any living room setup. Powered by Google TV, the Xiaomi TV A Pro 55 2026 offers easy access to streaming apps, voice control, content recommendations, smart-home integration, and seamless casting. It provides a smooth and user-friendly smart TV experience. Overall, this model combines excellent picture quality, smooth motion, strong audio, and smart functionality, making it an ideal 55″ 4K TV for movies, gaming, and everyday entertainment. Specifications: Display Type QLED Resolution 4K, 3840 × 2160 Speaker 2 x 10W Dimensions including base (L × W × H) 1226*312*770mm Dimensions not including base (L × W × H) 1226*76*711mm CPU Quad cortex A55 GPU Mali-G52 MC1 RAM 2GB ROM 8GB
WIWU SW03 Sports Smart Watch - Vermilion | Fitness Tracking, Heart Rate Monitoring, Sleep Analysis | Waterproof, Long Battery Life | Compatible with iPhone, Android, iPad, and Tablets WIWU SW03 Sports Smart Watch – Vermilion | Fitness Tracking, Heart Rate Monitoring, Sleep Analysis | Waterproof, Long Battery Life | Compatible with iPhone, Android, iPad, and Tablets WIWU SW03 Sports Smart Watch : Display: 1.28-inch TFT LCD, 240×240 resolution (full-round display) Sport Modes: 13 sport modes for fitness tracking Health Monitoring: Heart rate monitoring, sleep tracking, step counting Bluetooth Features: Supports Bluetooth calls and notification synchronization Water Resistance: IP68 rating (can be submerged up to 1.5m for 30 minutes) Battery: 200mAh, magnetic charging (full charge in ~2 hours) Battery Life: Over 25 days standby time Build Material: PC/ABS plastic for durability
The ViewSonic XG2409A 24″ 240Hz Gaming Monitor is built for gamers who need ultra-smooth and responsive performance. It features a 240Hz refresh rate, giving you ultra-fluid gameplay even in fast-paced scenes. With a 1ms response time, this monitor helps eliminate motion blur and ghosting, keeping visuals crisp and sharp. The Full HD resolution ensures clear image quality for gaming, work, or media. Its SuperClear® IPS panel provides vibrant colors and consistent brightness from any angle. This makes it ideal for competitive gamers and content creators alike. The ViewSonic XG2409A 24″ 240Hz Gaming Monitor includes AMD FreeSync™ support to prevent screen tearing and stuttering. This creates a seamless experience, especially in high-speed action games. It also supports HDR10, which improves contrast and detail in bright or dark scenes. Games, movies, and images look more lifelike and immersive. You’ll find useful connectivity options like HDMI and DisplayPort, giving you easy compatibility with consoles and PCs. There’s also a 3.5mm audio output for connecting your headphones or speakers. The ergonomic stand lets you adjust height, tilt, swivel, and pivot for all-day comfort. You can also mount it on a wall or arm with VESA support. An anti-glare screen reduces reflections and makes it easier to focus on gameplay, even in bright rooms. Its minimal design looks sleek and fits into any setup. In short, the ViewSonic XG2409A 24″ 240Hz Gaming Monitor offers fast refresh, clear visuals, and customizable comfort. It’s a powerful choice for gamers who want to stay ahead. Specifications: Display : 24″ IPS Resolution : 1920 x 1080 FHD Refresh Rate : 240Hz Response Rate : 1ms MPRT
The MSI Optix AG321CR Monitor delivers immersive gaming with a 31.5″ curved display and Full HD resolution. The 1500R curvature enhances field of view and comfort. Moreover, it features a 165Hz refresh rate and 1ms response time for smooth motion. This improves clarity during fast gameplay. The VA panel provides high contrast and deep blacks. It ensures consistent colors with wide 178° viewing angles. Adaptive Sync with AMD FreeSync Premium reduces screen tearing and stutter. This delivers fluid and stable performance in games. It also includes Night Vision to improve detail in dark scenes. Anti-flicker and low blue light features help reduce eye strain. The MSI Optix AG321CR Monitor is ideal for users who want large curved visuals and smooth gaming performance. Specifications: 31.5″ Full HD VA curved panel with 1500R curvature 165Hz refresh rate for smooth gameplay 1ms (MPRT) response time for reduced motion blur AMD FreeSync Premium for tear-free performance Wide viewing angles with high contrast ratio
