The Dual Fuel Fill adaptor is unique to the Discovery Series product line.
This adaptor comes complete with a CO2 or compressed air tank C GA-320
fitting with a .825-1 4 thread and a petcock valve, a 12" stainless steel
braided hose, a patented bleeder valve and a female Foster fitting. This
adaptor is made for both CO2 or compressed air. For compressed air charging
the Crosman unique bleeder valve is a necessity. To take full advantage of
the Discovery rifles this is a must have accessory.