This is an exceptionally rare excellent totally genuine BATF approved inert Finnish WWII M41 Sirpalekranaatti 41 Hand Grenade. This Finnish defensive grenade has a two piece cast body. Its fuse is a percussion type, which had to be struck on a hard surface to ignite the delay before throwing. Two safeties had to be removed, first the brass cap (after pulling the ring), and then the small clip around it's striker pin rod. The top and base of the grenade are connected by copper wire holds them together. Both top and base have 6 notches each over which the wire is wrapped. The fuse is an M32. Rather simple fuse design, but apparently reliable design which remained as the standard fuse type for these grenades through World War 2. Nothing suggests that there are real problems with fragmentation of these grenades (besides fragmentation pattern probably being very random - like in most hand grenades of the era) - on the contrary by end of World War 2 egg hand grenade 41 got replaced in production by quite similar egg hand grenade 43 and after the war they remained in use (equipped with new fuses) numerous decades. The reason why there was no problems with fragmentation might be related to fact that the Finns used only TNT in hand grenades that they manufactured - not some less effective explosive.