Carlson's Choke Tubes are manufactured from corrosion resistant 17-4 PH Stainless Steel. Carlson's Sporting Clays Thinwall Choke Tubes are not designed for 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 and feature a knurled extension to make removal quick and easy while in the field. Carlson's Sporting Clays choke tubes feature a Stainless Steel finish and are backed with a lifetime warranty.Notes: Not designed for use with steel shot.