These new sporting clay tubes are made from 1704 stainless steel and precision machined to produce a choke tube that patterns better than standard choke tubes. These choke tubes feature a 25% larger parallel section in the choke, thus throwing more consistent patterns than conventional choke tubes. Each choke tube is knurled on the end to allow for quick and easy removal. Plus, they have the constriction laser etched on the end for easy reference. Lifetime warranty. For 12-gauge models only. Fits all Browning Invector, Mossberg Model 500, Winchester, Weatherby & Savage 12 gauge Choke Systems.