Tank Valve O-Ring. Urethane. Industry standard - will fit all CO2 valves and HPA relgulators.
Guardian Large Piston Oring #10
Guardian Small Piston Oring #17
Fill Nipple O-Ring (4/90) - Replaces the 4/90 oring inside your tank's fill nipple.
Oring Kit designed specifically for the PTC Female Unit by Killhouse Weapon Systems.
JT CO2 Oring Kit - 10 Pack