Description copied from FM 23-30-1944 :
This grenade is a common glass pint bottle equipped with a with a crimped metal cap and is used with the following chemical fillers: FS, AC, NP, and IM. No bursting charge is provided. Dispersal of contents i produced when the bottle is shattered by impact. When the frangible grenade M1 is filled with incendiary filler NP or IM, it is equipped with the M3 igniter. This igniter consists of an igniter fuze body, a striker, and a blank cartridge, and is fastened around the bottle with a Timmerman strap. Before throwing, the safety pin must be removed. When thrown, the bottle breaks, releasing the strap and strap safety. This permits the striker, which is actuated by the striker spring, to ignite the blank cartridge. The flash from the blank cartridge ignites the contents of the broken bottle.