Think of the standard military cap for a civil war long gun as a top hat. it has the cap and then flanges out the bottom. the flanges make it easier to remove after friing. when fired the flanges "spring" up to the striking flat part of the cap. There are a couple of manufacturers. CCI makes 2 different caps one for reenactors, and a standeard cap. On the outside of their tins it is clearly marked "musket cap", or "musket reenactor cap". The RWS have the No. 1081 on the red label, and if you can find them, they are still out there Navy Arms Co. the ones that I have found come in a metal tin that states wing musket caps Model 2000. The wingless caps are a bugger to remove from muskets. they seem to mold to the nipple(cone). Anyway the ones I have treid have. I have a tin of those floating around the house that someone gave me.