Remington Aftermarket O-Ring Replacement Barrel Seal (Model 1100 12 GA, 11-87 12 Gauge) Replacement o-ring for Remington 1100, 11-87 12 Gauge Highest grade synthetic rubber o-rings replace old, worn, or cracked orings to provide a proper seal and restore gas system reliability Used to resolve blow back issues with 12 gauge gas ports for Remington 1100 & 11-87 shotguns Chemical resistant Genuine DuPont Viton resists solvents used to clean firearms Viton has high temperature, compression, and operational tolerances. Up to 316 C (600 F) and down to -54 C (-65 F) Ships and sold from Professor Foam, any other sellers are not genuine Professor Foam branded items