Ergotron Mounting Arm for Keyboard, Mouse 20-inch height range allows users to move between sitting and standing positions during data entry Extends keyboard up to 42" Fold the keyboard back out of the way when not in use Ergonomic back-tilt keyboard tray ensures wrists remain in a neutral position during data entry - avoid repetitive-stress injuries while increasing comfort and productivity Mouse tray slides out to left or right, depending on user preference