Custom cast, high density, bright orange foam (read - inert). Weigh 4oz (flashbang) & 6oz (MkII). Working on an M26A1 and the M67, both will be 6oz. MkII, M26 and M67 will come with approx. 4 foot orange "tails" to help with recovery, flashbang does not have a tail. I made a few dozen of these last year had some at the late season games and people seemed pleased, but most people wanted ones that go bang.