These are the highest qualitySolid Black Teflon Coated O-rings that will work with Co2, Nitro, or Compressed Air! 

Fits All Size Tanks - All Standard Tank Necks. 

These o-rings are made from high quality Buna/Nitrile, and are the proper 90' S/A durometer hardness to handle high compression air and other air mixture applications.  "These type of o-rings are what the Pro's use." 

There is absoultly NO Leaking with Buna/Nitrile O-Rings comapred to silicone and urethane type o-rings.  Buna/Nitrile O-Rings are the best for a high pressured tank seal to paintball  marker.

This Buna/Nitrile rubber substance is more resilient than silicone and urethane, hold their shape better, and can handle a lot wider array of climate temperatures from super cold to blistering hot.   All O-rings use a measurement called durometers.  This is the measurement of hardness.  Most O-rings you will buy will have 70 durometers in hardness.  These O-rings have a higher hardness of 90 durometers.  This hardness combined with the Buna Nitrile makes these the longest lasting O-rings you can get, Guaranteed!