The Teardrop Mouse Tray by Dexterity Platforms attaches to most chairs using the included velcro straps, providing you a mouse tray which can be conveniently located at the end of your chair arm. This allows you use your mouse while leaving your arm resting on your chair arm, and ensures that there is no 'reach' for the mouse. Units can clamp onto chair arms that are from 1.7" (4.3 cm) to 3.25" (8.25 cm) wide.