Carlson's Sporting Clays with a BLACK FINISH are made from 17-4 stainless and precision machined to produce a choke tube that patterns better than standard choke tubes. These choke tubes feature a 25% longer 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 or installation. Each choke has the constriction lasered on the end for easy reference. These choke tubes may be used with Lead Copperplated Nickle Hevi-Shot Bismuth Tungsten or Steel shot. Steel shot larger than BB and Steel shot faster than 1550 FPS cannot be used in the Full or EF constrictions. These chokes are backed by a lifetime warranty.