3M Adjustable Keyboard Tray Knob Adjust Keyboard Tray features a basic knob adjust arm that controls both height and tilt. Gel wrist rest has antimicrobial protection that inhibits the growth of microorganisms, such as bacteria. Keyboard tray has a tilt range of +15/-15 degrees, 360 degree swivel and unlimited positions within height range. Height adjusts 1-1/2" above work surface and 4-1/2" below work surface. Mouse surface can mount left or right. Keyboard tray is designed for standard workstations that can accept a 17-3/4" track. Tray is made with a high percentage of recycled material.