Fit flush with the end of the barrel but are longer than competitors' tubes; 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 the shot column entering the choke; Gas is controlled at the interface between choke and where it seats in the bore; Patterns tighten consistently and reliably; Patterns tighten consistently and reliably