4 Winchester Super-X Model 1 O-Ring Replacement Barrel Seals [Graphite Coated] Replacement o-ring for Winchester Super-X, Model 1 12ga Semi-Auto Shotgun (same as Remington 11-87 12ga Barrel Seals) Highest grade synthetic rubber (graphite coated) 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 gas ports for Winchester Super-X Model 1 Material has high temperature, compression, and operational tolerances. Up to 316 C (600 F) and down to -54 C (-65 F) Manufactured and warrantied by Captain O-Ring LLC