The Ideal (right hand) keyboard tray includes a mechanism, tray and wrist-rest. With this keyboard tray kit, with its easily adjustable height, without any knob or control lever, your keyboard and mouse will always be at an ideal height. You will assume a more ergonomic posture, and therefore avoiding physical problems such as RSI (Repetitive Stress Injury) or MSD (musculoskeletal disorder). It's size and specifications are a good fit for most workstations, and a must for a more ergonomically sound workstation.