The Mk 2 grenade, commonly known as the "Pineapple" grenade, is a hand grenade used by the United States military. It was first introduced during World War II and features a distinctive grooved exterior that resembles a pineapple. This design helps to create shrapnel upon detonation, increasing its lethality. The Mk 2 grenade is typically filled with a high-explosive material and has a safety lever and pin mechanism for safe handling. It has a delay fuse that allows the user to throw the grenade before it explodes, making it effective in combat situations. The grenade has been largely replaced by more modern designs but remains a symbol of military history.