This Metal Adjustable Dose Repeater from Prodigy Instruments features an easy CDS System. Just Click (Click the button), Draw (Draw in fluid) and Squeeze (Squeeze to deliver). Comes with UV resistant poly barrel and versatile blue o-ring that is compatible with oil based vaccines. Ergonomic comfort grip metal handle and lever. Includes 3 colored knobs (GREEN, YELLOW, BLUE and ORANGE)- same colors as your Cross Five Cattle Cooler holster tubes!