Co2 Fill Adaptor A simple and easy way to fill your Discovery series rifle with CO2This CO2only fill adaptor is made exclusively for the Discovery series rifles. It consists of a C GA -320 fitting with a .825-1 4 thread, a braided stainless steel 8" hose and a female Foster fitting. This adaptor is made for use with current CO2paintball tanks. For compressed air or Dual Fuel charging use the FAH002 adaptor.