Palmetto State Armory Dagger Thread Protector Replacement O-Ring 5 Pack. Works with Dagger, Dagger Micro & 5.7 Rock Thread Protector for Threaded Barrels.O-Rings are made from VitonA(R) Fluoropolymer Elastomer synthetic rubber, which provides chemical resistants and extreme temperature capabilities from as high as 400AdegF/200AdegC and as low as -17AdegF/-27AdegC. This material gives excellent tension to prevent movement of your PSA Dagger or 5.7 Rock barrel's thread protector.