Carlson's Choke Tubes Remington 1100 12ga Bulk O-Ring 100Pack (00167) Remington Model 1100 & 11-87 12 Ga Shotgun O-Ring Replacement: Synthetic rubber and fluoropolymer elastomer. Superior material for the gas system barrel seal. Features: - High-grade synthetic rubber O-rings replace old, worn, or cracked rings to provide a proper seal and restore gas system reliability - Resolve blow back issues with 12 gauge gas ports for Remington 1100 & 11-87 Shotgun - Will resist many solvents used to clean firearms - Material has a high tolerance to compression and operational at an extreme heat of 316°C(600°F) down to a freezing -54°C(-65°F)