This is a rubber replacement tip for Blichmann's BeerGun. The small tip is responsible for controlling the flow of beer out of the BeerGun, and for such a small component, is critical! If the tip is lost or becomes damaged, the BeerGun will not function properly. Having one or two of these on hand is cheap insurance to ensure a smooth bottling day with your BeerGun. Fits easily on the metal stopper tip of the gun.