Carlson's Choke Tubes are manufactured from corrosion resistant 17-4 PH Stainless Steel. Carlson's Sporting Clays Choke Tubes are designed for Lead, Copperplated, Nickel, Hevi-Shot, Bismuth, Tungsten or Steel shot. They feature a 25% longer parallel section which creates a denser pattern and reduces the occasional flier. The Sporting Clays Choke Tubes extend 3/4" outside the barrel which eliminates damage to the barrel caused by prolonged steel shot use, they feature a knurled extension, Stainless Steel finish and are backed with a lifetime warranty.