Our awesome Viton o-rings are now available in the Bore-Up size!
 
Viton® O rings have excellent chemical resistance and can be used at temperature range of between -15°C and 180°C. Although generally more expensive than NBR (Nitrile) O-rings, FKM has found wide acceptance in the aircraft, automotive and chemical industries. 

These O-Rings are the finest available for airsoft use and fit perfectly in all Bore-Up sized AEG piston heads and cylinders we've tested so far including Systema, Airsoft-Parts.cz and ICS. 
 
These o-rings come in 75shA (Black) which is ideal for virtually all builds.

We recommend lubricating the piston head O-Ring with liquid silicon oil or a thin PTFE based grease.
 
Please note that colours may vary with batch.