Under Desk Retractable, Easy-to-Assembly Desk Extension Tray for Writing in the Office at Home Description: [STURDY MATERIAL] Keyboard shelf clamp and akcesoria are made of durable and durable steel, wear-resistant, thickened material, with high load capacity and more stable. [ROTATION] It can be rotated 45° to achieve an irregular tabletop thickness within 4 cm for different L-shaped corner tables. [WRIST PROTECTION] A set of clamps and rails for the DIY keyboard shelf, and the wrist is naturally relaxed, avoid bending, effectively avoid wrist pain and more comfortable to operate. [EASY TO INSTALL] Easy to install clamp and rails, then clamp it on your desk, no need to punch, no damage to your desktop, easy installation. [DESIGN] The elongated guide can be extended by 20 cm, smooth solid steel balls make the guide quieter, the guide can be removed and separated, it is easy to clean, simple and convenient. Specification: Material: metal Size Chart: cm - cm /7.87in-15.75in The package includes: 1 set of keyboard shelf clamp rails (does not include wooden board)