Browning Invector DS Extended Choke Tube - 12ga SPECIFICATIONS BRAND: BROWNING DESCRIPTION Keeps going and going. This is a choke tube that is long on length and even longer on performance. Each tube extends beyond the end of the barrel for easy removal and for the most even, tight patterns in Browning's history of choke tube design. Proprietary differential banded gas seal eliminates residue build up and makes chokes easy to remove and install Integrated spring suspension holds the seal tight, yet allows expansion against the barrel wall for a perfect fit and a smooth transition for shot column entering choke Gas is controlled at the interface between choke and where it seats in the bore From skeet to full choke, patterns tighten consistently and reliably Invector-DS tubes fit only Browning shotguns designed for Invector-DS and are not for use in shotguns showing Invector-Plus or Standard Invector on the barrel(s).