Carlson Gas O-Ring Assortment Kit has all different sizes of O-Rings. The O-Rings are coated with graphite so that they have longer lasting performance. These gas O-Rings can get the job done in most gas operated shotguns, especially if your shotgun is part of the following list.
O-rings work with: Remington Model 1100, 11-87, Pro Bore Guns, G-3 models, Beretta
Shotguns, Winchester Shotguns, Franchi Shotguns, Charles Daly Shotguns,
Tri Star Shotguns, EAA Shotguns and many other shotgun types. These O-rings work for 28, 20, and 12 gauge shotguns.