High-grade silicone rubber O-rings replace old, worn, or cracked rings to provide a proper seal and restore gas system reliability. Fits a wide variety of 12- and 20-gauge shotguns. 20-gauge rings will fit many 28 gauge shotguns, too. Mfg: Carlsons SPECS: Rubber, black. Fits Remington 1100/11-87, Beretta, Winchester, Franchi, Charles Daly, Tri-Star, EAA, and others. Kit contains (4) 12 gauge rings and (2) 20 gauge rings.