These are the replacement o-rings commonly on the Tank Valve right above the threads. This is a necessary item needed for both speedball and woodsball players to have a proper seal. The O-Rings are...
HK Army Tank Regulator Bonnet (Single O-Ring)
This is a standard replacement bonnet for HK Army tanks. This is the top part of a 2 piece regulator that is found on the top of the HK Army...