Helps counteract the painful effects of recoil using mercury, one of the heaviest, densest, liquid elements. Compact, permanently sealed, steel case is made from bar stock; the only moving part is the liquid mercury so there's no wear, no chance of leaks. Mercury's viscosity varies only 1% from 0 F. to 90 F. which means the recoil-fighting performance is consistent in almost all weather conditions. Stock models fit in the rifle or shotgun stocks and are drilled and tapped 1/4"-28 tpi for easy installation and removal. Mercury Recoil Sizes Mfg: C & H Research SPECS: Machined, stainless steel tubes. Stock 4" A - 7/8" " dia. (22mm), 11 oz. wt. Stock 4" B - 3/4" (19mm) 8oz. Standard Stock 4.25" x 11/16" (17mm) dia. 8 oz. Short Stock 3' x 7/8" (22mm) dia. 8 oz., Stock - 5" A - .750" (19mm) di