Laptop Battery Compatible for A31N1519 Battery for ASUS X540S X540L X540SA X540S X540LA-SI302 A540 F540 R540LA About this item Compatible model no. :- a31n1519, asus x540s x540l x540sa x540s x540la-si302 a540 f540 r540la Warranty not covered if defects due to external causes, accidental, physical or liquid damage, cut, burnt, misuse and missing warranty stickers or labels Battery capacity/power capability (mah/wattage) may be different from the reference picture but a backup of the battery will be the same as the original Please match your product with the image provided before placing the order for any help please get in touch with us.
Genuine-spec US layout keyboard replacement for MacBook Pro (Model A1398, Late 2011–Mid 2012)—featuring durable scissor-switch keys, backlighting, and OEM-fit design for reliable typing and straightforward installation. Compatible With: MacBook Pro 13″: Late 2011 (Model A1278, but labeled A1398 in some regions) – Model Identifier MacBookPro8,1 MacBook Pro 15″: Early 2011, Late 2011, and Mid 2012 – Model Identifiers MacBookPro8,2 (15″ early/late 2011) and MacBookPro9,1 (15″ mid 2012) *(Note: “A1398” is primarily associated with the 15″ unibody MacBook Pro with Retina display (Mid 2012), which was the first Retina MacBook Pro.)* This keyboard fits the non-Retina 15″ A1398 (Mid 2012) and compatible Late 2011 models. MacBook Pro 13″: Late 2011 (Model A1278, but labeled A1398 in some regions) – Model Identifier MacBookPro8,1 MacBook Pro 15″: Early 2011, Late 2011, and Mid 2012 – Model Identifiers MacBookPro8,2 (15″ early/late 2011) and MacBookPro9,1 (15″ mid 2012) *(Note: “A1398” is primarily associated with the 15″ unibody MacBook Pro with Retina display (Mid 2012), which was the first Retina MacBook Pro.)* This keyboard fits the non-Retina 15″ A1398 (Mid 2012) and compatible Late 2011 models. Layout: Standard US English (QWERTY) with full-size keys, inverted-T arrow keys, and dedicated function row (F1–F12). Keyboard Type: Traditional scissor-switch mechanism—robust, tactile, and serviceable (pre-Butterfly era). Integrated Features: Backlit keys (adjustable brightness via F5/F6) OEM ribbon cable with ZIF connector Matches original key spacing and actuation force Backlit keys (adjustable brightness via F5/F6) OEM ribbon cable with ZIF connector Matches original key spacing and actuation force Build & Fit: Precision-molded plastic frame with exact screw mounts and alignment pegs—ensures secure, rattle-free installation in the top case. Installation Note: Keyboard is secured with screws and minimal adhesive. Requires full top case access and battery disconnect. Recommended for intermediate to advanced users or technicians.
Philips 346B1C 34-inch curved ultrawide monitor delivers wide workspace and efficient multitasking for professional use. It focuses on UltraWide clarity, USB-C docking, and ergonomic comfort for daily productivity. Additionally, it features a 34-inch VA panel with UltraWide QHD resolution (3440 × 1440). This resolution provides more horizontal space, so it improves multitasking and side-by-side workflows. Moreover, it uses a 1500R curved design. As a result, it creates a more immersive viewing experience and keeps content within a natural field of view. The monitor supports up to a 100Hz refresh rate with 4ms response time. Therefore, it delivers smooth visuals for office work, media, and light gaming. In addition, it includes USB-C docking with power delivery up to 90W. This allows video, data, and charging through a single cable, so it simplifies desk setup. Furthermore, it features Adaptive Sync, MultiView (PIP/PBP), and built-in Ethernet. These features improve workflow flexibility and connectivity across multiple devices. It also includes Flicker-Free and LowBlue Mode. So it helps reduce eye strain during long working sessions. Philips 346B1C 34-inch curved ultrawide monitor provides a large immersive display, strong connectivity, and productivity-focused features for modern work environments. Specifications: 34-inch VA panel with 3440 × 1440 UltraWide QHD resolution 100Hz refresh rate with 4ms response time 1500R curved design for immersive viewing USB-C docking with up to 90W power delivery MultiView, Adaptive Sync, and built-in Ethernet connectivity
WiWU WM108 Wimice Dual‑Mode Mouse – Bluetooth 5.0 and 2.4 GHz wireless mouse with 800/1200/1600 DPI, silent clicks, and ergonomic ABS housing.Long battery life (~6 months standby), USB dongle & silent design—ideal for travel, office, and quiet environments. Model: WiWU Wimice WM108 Connection Modes: Bluetooth 5.0 2.4 GHz wireless via USB dongle Connection Modes: Bluetooth 5.0 2.4 GHz wireless via USB dongle DPI Settings: 800 / 1,200 / 1,600 DPI (adjustable) Buttons: 3 standard buttons + clickable scroll wheel (4 keys total) Range: Up to 10 m wireless connectivity Material/Design: Lightweight (67–130 g, depending on source), ergonomic ABS plastic body, magnetic base or “super magnetic absorption” design Operating Range: ≈10 m Silent Clicks: Quiet operation—silent key action Dimensions: Approx. 108 × 64 × 36 mm Weight: 67 g cited by Star Tech and 130 g by others—likely lighter in official spec Compatibility: Windows, macOS, Linux, Android, etc. Plug-and-play, no driver needed
The BenQ ZOWIE XL2566K TN 360Hz 24.5″ Gaming Monitor is designed for serious gamers. Its 360Hz refresh rate ensures incredibly smooth and fluid motion, reducing blur and ghosting in fast-paced games. With a 24.5″ TN panel, this gaming monitor delivers vibrant colors and sharp images. The TN technology ensures low response times, making it ideal for competitive gaming where every millisecond counts. Setting up the BenQ ZOWIE XL2566K is simple and straightforward. The adjustable stand allows you to find the perfect viewing angle, ensuring comfort during long gaming sessions. Experience the benefits of DyAc+ Technology, which enhances clarity and reduces motion blur. This feature is perfect for first-person shooters and fast-action games, giving you a clear advantage over your opponents. The BenQ ZOWIE XL2566K offers multiple connectivity options, including HDMI, DisplayPort, and USB. This versatility allows you to connect various devices and switch between them with ease. With its Black eQualizer and Color Vibrance settings, you can customize your gaming experience. These features help you spot enemies in dark areas and adjust color settings to suit your preferences. In conclusion, the BenQ ZOWIE XL2566K TN 360Hz 24.5″ Gaming Monitor is a top choice for gamers seeking an edge in performance. Upgrade to this monitor and enjoy ultra-smooth gameplay and exceptional clarity. Elevate your gaming setup today and dominate the competition. Specifications: Display : 24.5″ TN Resolution : 1920 x 1080 Refresh Rate : 360Hz
Genuine-spec touchpad flex cable for MacBook Air 13″ (Model A1534, Early 2015)—essential for restoring full trackpad functionality, including precise cursor control and physical click response, during repair or replacement. Compatible With: MacBook Air 13-inch (Early 2015, Model A1534, Model Identifier MacBookAir7,2). Part Type: Touchpad flex cable only—does not include the trackpad housing, button mechanism, or mounting brackets. This is the ribbon cable that connects the trackpad to the logic board. Function: Carries input signals from the trackpad to the logic board—critical for cursor movement, tap-to-click, and primary/secondary physical click functionality. (Note: This model uses a physical click mechanism, not Force Touch—so no haptic feedback or pressure-sensing.) OEM-Quality Construction: Matches Apple’s original cable in length, connector type, and shielding—ensures reliable signal transmission and long-term durability. Common Use Cases: Replacing a torn, frayed, or damaged original flex cable Completing a trackpad replacement when the original cable is compromised Fixing erratic cursor movement, unresponsive trackpad, or loss of click function Replacing a torn, frayed, or damaged original flex cable Completing a trackpad replacement when the original cable is compromised Fixing erratic cursor movement, unresponsive trackpad, or loss of click function Installation Note: Requires bottom case removal and careful disconnect/reconnect of the ZIF (Zero Insertion Force) connector on the logic board. The cable routes under the battery—handle with care. Suitable for intermediate to advanced DIYers or technicians.
The Lexar NM620 2TB NVMe SSD delivers exceptional read speeds up to 3,300 MB/s and write speeds up to 3,000 MB/s through its PCIe Gen3x4 NVMe 1.4 interface. Built with 3D NAND Flash and a compact M.2 2280 form factor, it offers fast, efficient, and reliable storage for gaming, video editing, and professional workloads. The Lexar NM620 2TB M.2 2280 NVMe SSD is engineered for users who need high-performance storage without compromise. Using PCIe Gen3x4 lanes and the NVMe 1.4 protocol, it provides up to six times faster transfer speeds than SATA SSDs. Its slim, cable-free design makes it an ideal upgrade for desktops, laptops, and ultrabooks that demand higher data throughput and improved responsiveness. ⚡ High-Speed NVMe Performance: Delivers sequential read/write speeds up to 3,300 MB/s / 3,000 MB/s for faster system boot-ups, game loading, and large-file transfers. 💾 Large 2 TB Capacity: Provides ample storage for 4K media, applications, and high-volume project files. 🔋 Power-Efficient Design: Optimized for lower power draw, helping extend laptop battery life and reduce operating temperatures. 🔒 Advanced Data Protection: Utilizes LDPC (Low-Density Parity-Check) and end-to-end data path protection for accurate, consistent data integrity. 🧊 Compact Form Factor: The M.2 2280 design supports easy installation in modern systems without cables. 🧠 3D NAND Architecture: Ensures improved endurance, sustained performance, and stability during intensive workloads. 🧰 Durability Tested: Resistant to shock and vibration for dependable performance across a range of operating environments.
REMAX RM-C45 Mena Aroma Diffuser Portable Humidifier, Mini Diffuser for Car Home Office Bedroom with Smart Connectivity, Remote Control, Long-Lasting Fragrance and Mesmerizing Starlight Effect, Black About this item Dual Purpose Design: Perfectly suited for both car and home use, this aroma diffuser enhances any space with delightful fragrances, whether you’re on the road or relaxing at home. Starlight Effect: Create a mesmerizing ambiance with the starlight effect, projecting a soothing light pattern that complements your favorite scents for a relaxing experience. Smart Connectivity: Enjoy modern convenience with smart connectivity features that allow you to control the diffuser remotely, ensuring ease of use and customization from anywhere. Long-Lasting Fragrance: Formulated for extended scent release, this diffuser ensures that your environment remains fresh and inviting for hours on end, without the need for constant refills. User-Friendly Remote Control: The included remote control makes it easy to adjust settings and change fragrances without needing to reach the diffuser directly, providing ultimate convenience. Customizable Aromatherapy: Choose from a variety of essential oils or fragrances to create your desired atmosphere, whether you seek relaxation, invigoration, or a fresh ambiance. Compact and Stylish Design: The sleek and modern design fits seamlessly into any decor, enhancing your car’s interior or your home’s aesthetic without taking up too much space. Perfect Gift Idea: A thoughtful gift for friends or family who appreciate home fragrance and wellness, making it a great addition to any special occasion or celebration.
The LG 27U511SA-W 27″ FHD IPS Smart Monitor with Speakers is built for comfortable viewing, entertainment, and everyday productivity. Its 27-inch Full HD IPS display delivers clear visuals and consistent colors, making it suitable for work, streaming, and browsing. Moreover, the IPS panel ensures wide viewing angles so images remain accurate from different positions. This smart monitor allows direct access to streaming apps without requiring a connected PC. Additionally, the built-in speakers provide convenient audio for movies, meetings, and casual gaming without external devices. The slim and modern design fits easily into home or office environments while keeping your workspace clean and organized. Connectivity options allow easy connection to laptops, consoles, and media devices. Furthermore, ergonomic adjustments help users maintain comfortable viewing positions during long sessions. Therefore, the monitor suits home users, students, and professionals seeking versatility and convenience. Finally, it combines smart functionality, quality visuals, and built-in sound for daily entertainment and productivity needs. Specifications: 27-inch Full HD IPS smart monitor Built-in speakers for convenient audio Smart features for direct streaming access Wide viewing angles with accurate colors Modern design with versatile connectivity
A reliable pre-owned HP EliteBook 840 G3 with 14" display, 6th Gen Core i5, 8GB RAM, and 256GB SSD—offering solid business performance, security, and durability for everyday professional use.
The ViewSonic VX24G10 24″ FHD 240Hz Gaming Monitor delivers ultra-smooth visuals ideal for gaming and daily use. It displays Full HD resolution with bright colors and crisp detail. The screen uses an IPS panel for wide viewing angles and accurate color. This makes movies, work, and games look clear and vivid. Moreover, the VX24G10 offers a blazing 240 Hz refresh rate. It reduces motion blur and makes fast movements appear fluid. This is especially helpful in competitive games or fast action scenes. The 1 ms response time ensures quick pixel transitions for sharp results. It helps avoid ghosting and lag during gameplay. In addition, the monitor includes modern connectivity options: multiple HDMI ports and DisplayPort. These ports let you connect PCs, laptops, and consoles easily. This flexibility supports many devices without trouble. The monitor also supports adaptive sync (FreeSync / G-Sync), which reduces screen tearing and ensures smooth frame rates. Furthermore, the ViewSonic VX24G10 features eye-friendly technology. Its flicker-free panel and blue-light filter help reduce eye strain during long sessions. The slim bezel design gives a modern look and saves desk space. The stand allows slight tilt adjustment for comfortable viewing angles. Also, the monitor supports HDR10, enhancing contrast and improving dynamic range for richer images. This adds depth to games, movies, and creative work. The combination of IPS quality, fast refresh, and HDR makes the VX24G10 a versatile choice for both gaming and productivity. Overall, the ViewSonic VX24G10 24″ FHD 240Hz Gaming Monitor offers smooth motion, sharp visuals, strong compatibility, and eye care. It is perfect for gamers, creators, and anyone who values performance and comfort. It enhances every task — from gaming to work to watching media. Specifications: Display : 24″ IPS Resolution : 1920×1080 Refresh Rate : 240Hz Response Time : 1ms
The HP Series 5 Pro 23.8″ FHD USB‑C Conferencing Monitor delivers crisp visuals on a 23.8‑inch Full HD IPS screen with a 16:9 aspect ratio. Additionally, it features a built‑in 5 MP Poly Studio tiltable webcam. This webcam, combined with AI noise reduction, ensures clear video and audio during calls. Moreover, the monitor supports USB‑C video input with up to 100 W power delivery. It also provides USB‑C data transfer, HDMI 2.0, DisplayPort 1.4, USB‑A ports with one charging port, an audio combo jack, and an RJ‑45 Ethernet port. These connections simplify hybrid work setups. Furthermore, the ergonomic stand allows height adjustment for comfort. The ambient light sensor with HP Eye Ease reduces blue light while preserving color accuracy. The monitor incorporates recycled materials in its design and comes with a three‑year limited warranty for peace of mind. Specifications: 23.8″ Full HD (1920 × 1080) IPS display with 350 nits brightness and 1500:1 contrast Built‑in 5 MP Poly Studio webcam with AI noise reduction USB‑C video with up to 100 W power delivery and USB‑C data port HDMI 2.0, DisplayPort 1.4, USB‑A ports, Ethernet, and audio combo jack Ergonomic stand with height adjustment and HP Eye Ease ambient light sensor
A next-generation Wi-Fi 6 router delivering AX1500 speeds (1201 Mbps on 5GHz + 300 Mbps on 2.4GHz), 4 high-performance antennas, and Gigabit ports—ideal for 2–3 bedroom homes needing faster speeds, lower latency, and seamless connectivity for 100+ devices. The TP-Link Archer AX12 is a powerful Wi-Fi 6 (802.11ax) dual-band router engineered for modern connected homes. With a combined speed of AX1500—delivering up to 1201 Mbps on the 5GHz band and 300 Mbps on the 2.4GHz band—it provides significantly faster throughput, reduced latency, and improved capacity compared to older Wi-Fi standards. Powered by a 1 GHz dual-core processor and equipped with four fixed high-performance antennas, the Archer AX12 delivers strong, stable coverage throughout 2–3 bedroom homes, eliminating dead zones and buffering. Advanced beamforming technology focuses Wi-Fi signals directly toward connected devices for clearer, stronger connections—even at greater distances. OFDMA + MU-MIMO: Efficiently serves multiple devices simultaneously—perfect for households with smartphones, laptops, smart TVs, and IoT devices connected at once (supports 100+ devices). www.wifi-stock.com WPA3 Security: Next-generation encryption for stronger protection against unauthorized access and cyber threats. www.amazon.in Backward Compatibility: Works seamlessly with all existing Wi-Fi devices (802.11a/b/g/n/ac/ax). www.tp-link.com Wired connectivity includes one Gigabit WAN port and three Gigabit LAN ports for high-speed connections to desktops, game consoles, NAS devices, or smart TVs. Parental Controls: Set schedules, filter content, and manage screen time per device QoS (Quality of Service): Prioritize bandwidth for video calls, gaming, or streaming TP-Link Tether App: Easy setup and management from your smartphone
HP M24f Monitor Overview The HP M24f is a 24-inch Full HD monitor designed for work and everyday use. It offers a slim design and reliable performance. As a result, it suits offices, home setups, and students. 24-Inch Full HD Display This monitor features a 24-inch Full HD resolution. Therefore, text appears sharp and easy to read. Moreover, images look clear and well balanced. Because of this, it supports long working sessions comfortably. In addition, the wide viewing angles improve screen visibility. As a result, content stays clear from different positions. Smooth Visual Performance The HP M24f delivers smooth visuals for daily tasks. As a result, scrolling and browsing feel natural. Furthermore, the display maintains consistent brightness. This improves overall viewing comfort. Eye Comfort and Anti-Glare Screen This monitor includes eye comfort features. Therefore, it helps reduce eye strain. In addition, the anti-glare coating minimizes reflections. As a result, users can work comfortably in bright rooms. Connectivity and Compatibility The HP M24f includes HDMI and VGA ports. As a result, it connects easily to modern and older devices. Moreover, setup is quick and simple. Therefore, users can start working right away. Slim Design and Mounting Options The monitor features a sleek and modern design. In addition, it supports VESA mounting. As a result, users can save desk space and customize layouts. Ideal for Daily Use This monitor focuses on clarity and reliability. Moreover, it suits office work, browsing, and media viewing. In conclusion, the HP M24f offers a balanced and efficient display solution. Specifications: 60.5 cm (23.8) FHD (1920 x 1080) Sustainable; Adaptive Sync; Eyesafe® Certified; IPS panel 1 VGA; 1 HDMI 1.4 (with HDCP support)
WiWU S500 Foldable Lightweight Plastic Laptop Stand Description WiWU S500 Foldable Lightweight Plastic Laptop Stand Brand: wiwu Material: ABS+Aluminum alloy Foldable Height Adjustment. Laptop stand with foldable technology, light weight, easy to carry Adjustable from 20 to 40 degrees and height adjustable from 3.15 to 5.12 inches. There are 6 corners Compatible with laptops (11 inch-15 inch) Macbook, iMac, ipad, Microsoft Surface PR, Thinkpad, Lenovo, Dell, HP and more. With anti-slip rubber pad
NB OMS040 OMS040 NB STAND DESK TV INNOVATIVE SIT STAND DESK MOUNT: UNIVERSAL COMPATIBILITY: Fits Most 22” – 32” Monitor with the load from4.4 lbs up to 33lbs, VESA compliant 75x75mm 100x100mm. Come with ultra-widekeyboard tray, 25.6″L x13.4”W. Keyboard Tray pull out range 2”(50mm). FULL MOTION MOUNT: A Wide range of movements, The monitor can berotated and tilted effortlessly in any direction, Tilt Angel from +9°to -12°with acombined +3°to -3° degree landscape rotation, Upright range is 17.1’’(435mm) withswivel angel ±90 degrees. The mounts extension and retraction 50.4’’ (1280 mm) and3.9’’ (100 mm) display height adjustment. EASY INSTALLATION: Built in durable gas-strut to hover at any workingpositions, Simple installation and easy to use, effortless operation; Switches fromsitting to standing position in just a few seconds. HAT6 STAND 6 LCD/LED DESK MOUNT 12”-24”-JTD003II6 -MAX-LOAD:10KG -TILT:+/-10 degree- SWIVEL:180 degree H148 Specifications: Specifications COMPATIBILITY: Fits Most 22” – 32” Monitor with the load from4.4 lbs up to 33lbs, VESA compliant 75x75mm 100x100mm. Come with ultra-widekeyboard tray, 25.6″L x13.4”W. Keyboard Tray pull out range 2”(50mm). FULL MOTION MOUNT: A Wide range of movements, The monitor can be rotated and tilted effortlessly in any direction
VIEWSONIC MONITOR TD2423 Display Size (in.): 24 Viewable Area (in.): 23.6 Panel Type: VA Technology Resolution: 1920 x 1080 Resolution Type: FHD (Full HD) Static Contrast Ratio: 3,000:1 (typ) Dynamic Contrast Ratio: 20M:1 Light Source: LED VIEWSONIC MONITOR Brightness: 250 cd/m² (typ) Colors: 16.7M Color Space Support: 8 bit (6 bit + Hi-FRC) Aspect Ratio: 16:9 Response Time (Typical GTG): 7ms Response Time (GTG w/OD): 7ms Response Time (Typical Tr+Tf): 25ms Viewing Angles: 178º horizontal, 178º vertical Backlight Life (Hours): 40000 Hrs (Min) Curvature: Flat Refresh Rate (Hz): 75 VIEWSONIC MONITOR Blue Light Filter: Yes Flicker-Free: Yes Color Gamut: NTSC: 72% size (Typ) sRGB: 104% size (Typ) Pixel Size: 0.272 mm (H) x 0.272 mm (V) Touch Screen: IR, 10-point multi-touch Surface Treatment: Glossy, Hard Coating (7H) Cover Glass Thickness: 1.85mm CompatibilityVIEWSONIC MONITOR TD2423 PC Resolution (max): 1920×1080 Mac® Resolution (max): 1920×1080 PC Operating System: Windows 7/8.1/10/11 certified; macOS tested Mac® Resolution (min): 1920×1080 Connector VGA: 1 USB 2.0 Type A: 2 USB 2.0 Type B: 1 3.5mm Audio In: 1 3.5mm Audio Out: 1 HDMI 1.4: 1 DVI-D: 1 Power in: 3-pin Socket (IEC C14 / CEE22) Specifications: VIEWSONIC MONITOR TD2423 Display Size (in.): 24 Viewable Area (in.): 23.6 Panel Type: VA Technology Resolution: 1920 x 1080 Resolution Type: FHD (Full HD) Static Contrast Ratio: 3,000:1 (typ) 1 Year Warranty Manufacturer link
Candc DC-C2 Lavalier Dual Head Mic Buy Online in Qatar, record high quality sounds using this branded duel mic. Candc DC-C2 is a Dual Omnidirectional lavalier microphone, designed for Smartphones, DSLR, Camcorders, Audio recorders PC, etc. PRODUCT DETAILS OF CANDC DC-C2 LAVALIER COLLAR MICROPHONE FOR CANON NIKON DSLR CAMCORDER
POUT E3 Angle - Adjustable Angled Ergonomic Laptop Stand Riser - Notebook Computer Holder Compatible w/MacBook Air Pro Dell HP & More 11"-17" Laptops - Foldable & Portable w/ 5 Angles (Silver) POUT E3 Angle – Adjustable Angled Ergonomic Laptop Stand Riser – Notebook Computer Holder Compatible w/MacBook Air Pro Dell HP & More 11″-17″ Laptops – Foldable & Portable w/ 5 Angles (Silver)
The LG UltraWide 34″ 100Hz Curved Monitor offers an expansive 21:9 aspect ratio, providing ample screen space for multitasking and immersive viewing. Its 3440 x 1440 WQHD resolution delivers sharp and detailed visuals, enhancing both productivity and entertainment experiences. Featuring a curved display, this monitor ensures consistent color accuracy and wide viewing angles, making it ideal for creative professionals and gamers alike. The 100Hz refresh rate provides smooth motion, suitable for everyday tasks and casual gaming. Equipped with HDR10 support, the monitor enhances contrast and color range, bringing visuals to life with greater depth and realism. The sRGB 99% color gamut ensures vibrant and accurate colors, essential for photo and video editing. Connectivity options include USB Type-C, HDMI, and DisplayPort, allowing seamless integration with various devices. The USB Type-C port supports data transfer and power delivery, simplifying your workspace setup. The ergonomic stand offers height and tilt adjustments, enabling you to customize the monitor’s position for optimal comfort. Its sleek, virtually borderless design adds a modern touch to any workspace. In summary, the LG UltraWide 34″ 100Hz Curved Monitor combines high-resolution visuals, color accuracy, and ergonomic design, making it a versatile choice for professionals and enthusiasts. Specifications: Display : 34″ VA Resolution : 3440 x 1440 WQHD Refresh Rate : 100Hz Response Rate : 5ms GTG Curvature : 1800R