The Sporting Clays Choke Tubes 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% 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. Each choke tube has the constriction laser marked on the end for easy reference. Lead shot, Steel Shot, Copperplated Shot, Nickel Shot, Hevi-Shotshells, and Buck Shot can be used in our Sporting Clay Choke Tubes. Due to the thin wall design of this choke tube Steel shot cannot be used int eh Modified, IM, Full, or EF constrcitons. Specifications: – Fits: Beretta Optima HP 20 Gauge – Skeet – Diameter: . 620″