Holds full size keyboard and mouse. Slide is mounted under shelf to provide maximum tray width. Mounting hardware not included. Mouse pad tray is 10"W x 8"D (250 mm x 200 mm) and retracts out of the way when not in use. Fits up to 19.25"W x 9"D (489 mm x 230 mm) keyboards. Extends approximately 9" (230 mm) for full access to keyboard. Made of strong, lightweight aluminum.