The Code Black series of choke tubes from Patternmaster were created with for the hardcore hunter who demands the most from their equipment. They feature a nitride coating for superior durability in the toughest conditions, and utilize the Patternmaster wad stripping technology which produces extremely consistent patterns with a shorter shot string to help you put more pellets on target. The Patternmaster wad stripping technology slows the base of the wad, allowing the shot to exit the barrel before the wad for undisturbed and extremely consistent shot strings. The porting on this tube will also reduce recoil and muzzle jump to help you get back on target faster for more effective follow up shots. Code Black Duck and Goose choke tubes are designed for medium and extended ranges and will reduce shot string length by up to 70% helping you knock down more birds. Lead, Steel, Hevi-Shot.Specifications and Features: Approved for Steel Shot: Yes Cartridge: 12 Gauge Constriction: Duck Extended: No Finish: Bronze Material: 17-4 PH Stainless Steel Ported: Yes Rifled: No Thread Pattern: Benelli, Beretta Mobilchoke