These are excellent replacement orings for your C02 or Compressed Air tank. Always keep a bunch of these around or you'll be begging everyone in the staging area for a spare.
Umarex CO₂ capsules are distinguished by constant high pressure and uniform quality. The constant pressure ensures that each shot is the same as the previous one. The thread is free of burrs that could damage the seals in the gun.
Dirt, paint and other debris getting in your fill nipple works its way through your HPA tank, destroying seals and o rings in both your tank and marker.