The Invector DS choke tubes are the most innovative choke system to hit the market. Unique Double Seal design features a brass alloy ring around the base of the tube to effectively seal the area between the tube and the barrel wall against gas and residue that make the tube difficult to remove. The DS choke tubes remain significantly cleaner even under heavy use than other choke tubes. The thin wall configuration and longer overall length allows longer parallel surfaces for maximum shot pattern performance. Overall length: 3-1/4” Flush mount Brass seal Thin wall construction.UPC: 23614373520