Highest grade synthetic rubber o-rings with graphite coating replace old, worn, or cracked orings to provide a proper seal and restore gas system reliability. This is the same material used by the OEM when your firearm left the factory.
Used to resolve blow back issues with 12 gauge gas ports in shotguns.
Material has high temperature, compression, and operational tolerances. Up to 316 C (600 F) and down to -54 C (-65 F)