mount-it! keyboard drawer under desk with mouse platform, easy-glide sliding under-counter computer keyboard tray 21 inch wide mount-it! mount-it! keyboard drawer under desk with mouse platform, easy-glide sliding under-counter computer keyboard tray 21 inch wide, black maximize desk space and create a more efficient workspace simply by adding this under the desk sliding keyboard shelf to the mix. it has ample space for your keyboard and other office items if desired, as well as an attached mouse tray that mounts either on the left or right side of the keyboard tray. the pull out keyboard tray features a steel ball bearing track for a smooth and silent sliding action. easily slide it out when in use and slide it back in when not in use to keep it hidden and out of the way. install it at 3 different height levels to customize it to your height and positioning. this ergonomic setup allows you to keep your elbows bent at the optimal angle to reduce strain on your wrists and arms and to help prevent carpal tunnel. this tray is built with comfort in mind with its rounded off front edge, or waterfall edge as we call it, to keep your forearms and wrists comfortable while typing. it also features a sliding clamp on the keyboard tray surface to securely lock your keyboard in place. product features and specifications maximize your precious office space with this tray’s ability to slide in and out from under your desk 3 preset heights adjustable up to 1.25 inches ball bearing track for a smooth sliding action rounded edge for wrist and forearm comfort while typing ample space sitting at 21 inches wide and 11.75 inches deep sliding mouse tray can be mounted on the left or right side of the keyboard tray easy installation lets you start feeling the difference right away