RWS musket caps are designed for all modern muzzle loading guns and all types of powder including Pyrodex. Tin of 100. Ribbed "U", hot, sensitive, and consistent, non-corrosive, non-mercuric Sinoxid priming compound. Fast, even combustion, non-hygroscopic, extended shelf life. For all side locks and in-lines. Max. internal diameter: 0.17" (4.25 mm.) and miin. height: 0.17" (4.20 mm).