WHAT YOU WILL GET2 Types: Normal Extension Rails/ Adjustable Extension Rails, choose according to your need. Set includes 1 pair clamp, 1 pair rail, complete accessories, ideal for storing your keyboard. STURDY MATERIALKeyboard tray clamp and rails accessories are made of sturdy and durable steel, wear-resistant, thickened material, strong bearing capacity and more stable. UNDER THE DESKThe clamping range of the clip is about 2.3-5.8cm/0.91-2.28inch. The Under Desk Extension rail can be pulled out 20cm away from the edge of the desk, effectively keeping the distance between you and the computer monitor and protecting your eyes. WRIST PROTECTIONClamp and rails Set for DIY Keyboard Tray, and your wrist is naturally relaxed, avoiding bending, effectively avoiding wrist soreness, and more comfortable to operate. EASY TO INSTALLEasy to assemble the clamp and rails, and then clamp it on the desktop, no need to punch, no damage to the desktop, easy installation. Specification: Material: Metal Size Chart: Normal Rail Length: 20cm Adjustable Rail Length: Total 40cm Package Includes: 1 Clamp Rail Set For Keyboard Tray Note: Please allow slightly errors due to manual measurement and different monitors.