Break up time spent sitting and working by creating a sit-stand workspace in your home or office. Place this height-adjustable standing desk riser directly on top of your existing desk, squeeze the lever to move the desk into 1 of the 12 height positions and set up your keyboard and mouse on the tray - there's plenty of room for both. The gas springs (pneumatic pistons) let you switch between sitting and standing with ease and control. Smooth and controlled assisted lift. 12 height positions. Maximum height: 19-11/16". FlexiSpot desk riser (41"W) comes in black and has a removable keyboard tray. Tested to meet ANSI/BIFMA Performance Standards - Manufacturer testing has been conducted on this product to meet specific performance requirements and safety standards set forth by the American National Standards Institute (ANSI) and the Business and Institutional Furniture Manufacturers.