The original Flame n Go was made to replace the nipple on a conventional percussion arm. It was a multi piece affair that holds a small or large primer (I can't remember which) in a somewhat sealed manner. To use it you unscrew the top portion of the unit put the primmer inside and screw the top back on. Mountain State Muzzleloading Supplies carried them at one time, and I think Dixie Gun Works had them as well.
Rusty <><