Keep your air tanks fill nipple protected with the HK Army fill nipple cover. The cover can easily be snapped on and off with its ball bearing locking technology. The fill nipple cover ensures that no dirt or paintball debris clogs up the nipple and helps prevent air leaks or regulator / air tank internal damage
Fill Nipple Cover Details:
Machined aluminum cover 
Fits all one way valves / fill nipples on air system regulators
Easily pushed on and off fill nipple