CODE BLACK DECOY tubes will extend out the end of your barrel about 3/8" and have an effective range of out to 40 yards. CODE BLACK DECOY tubes pattern similar to improved cylinder constriction chokes on paper, however, the patented "stud ring" inside the tube creates a much shorter shot string. CODE BLACK DECOY are not ported but have a knurled end for hand tightening.Specifications and Features:SecureFit threading provides tight fitting with zero pressure lossMade of aircraft quality 17-4 Stainless SteelPorting reduces recoil and muzzle jumpStud Ring holds the wad cup for a fraction of a second to create the tightest and densest patternsHeat treated for maximum durability and coated in a titanium, non-reflective bronze finishMade in the USA