The VICTRA-12 internal choke is a specialized choke that sits in the front of the suppressor not in the shotgun's barrel. The choke of a shotgun determines shot string only. It has no bearing on shot speed (velocity) or distance (range). That is the choke does not alter the shotgun's power-it just controls how tight or spread out the pellets will be at a specific distance.The three different choke sizes are all made of 17-4 Stainless Steel and are all machined for our VICTRA-12 12ga modular shotgun suppressor. Made in the U.S.A. Length: 1.00" Diameter: 1.050" Material: 17-4 Stainless Steel Finish: Natural Stainless Caliber: 12ga