Unlike traditional O-rings, X-rings seal better under pressure instead of blowing out. These X-rings are sized to provide a tight seal in standard cylinder sizes. We recommend sizing your cylinder to reduce internal friction as well.

X-rings are compatible with piston heads with a single internal fillet, such as Ace1Arms Aluminum, Prometheus POM, and Lonex POM piston heads.

Due to the small radiuses on X rings, we do not recommend using them in ported cylinders.