EconoLine Arm is perfect for use in compact workstations. Lightweight and easy to operate, the EconoLine Arm is available with 360 degree swivel and is fully retractable for storage below the work surface. A single knob adjusts both height and tilt simultaneously. To unlock and adjust the arm, simply turn adjustment knob counter-clockwise, find preferred position, and tighten to lock. Compatible with all Weber Knapp keyboard trays and clamps.