Height Adjustment Kit for VIVO Keyboard Trays: This height adjustment kit gives you more flexibility with your VIVO under-desk tray. Compatible with the following series: 20' MOUNT-KB05ES, 27' MOUNT-KB05E, and 34' MOUNT-KB15EB (see full list below) Customized Tray Placement: With 0.5' to 2.5' of additional adjustment, you can enjoy more comfortable typing angles that relieve stress on your wrists and shoulders