SVL Bull Barrel DeResonator. Designed to go on any barrel that is 7/8" to 1 1/8" O.D. like Competition, Bull Barrels and Scope mounted shot guns. It performs exactly the same as its smaller brother, released in 2005. To find the peak performance spot, try shooting groups with the Bull Barrel De-Resonator located in different locations. Watch your groups shrink! Sims Vibration Labs Barrel De-Resonator.