The New LimbSaver Barrel De-Resonator is designed to dampen out unwanted vibration by shortening the overall settling time of the barrel. The accuracy benefit is immediate, providing sub-minute angle groups with over-the-counter factory ammunition. This easy-to-install unit simply slips over most standard barrels. Designed and manufactured with LimbSaver's proprietary NAVCOM (Noise and Vibration Control Material), and engineered for optimum performance utilizing Sims Vibration Laboratory's DTMS (Decay Time Modification System). If you are looking for performance & accuracy, trust LimbSaver, the makers of "Products That Work". Barrel de-resonator can be used on a muzzleloader without a ram rod Diameter 1.44 inches Inner diameter 0.45 inches