Also known as: Mk2, マークII手榴弾, Mk2手榴弾, マーク2手榴弾
A fragmentation-type anti-personnel hand Grenade introduced by the United States Military in 1918.
It was the standard issue anti-personnel grenade used during World War II, and also saw limited service in later conflicts, including the Korean War and Vietnam War. It replaced the failed Mk1 Grenade of 1917. The grooves and knobs gave the Mk 2 appearance of a Pineapple, and are the origin of the nickname.
It was gradually phased out of service as the M26-series grenade was introduced during the Korean War. Due to the tremendous quantity manufactured during WWII, the Mk 2 was still in limited issue with the United States Army and United States Marine Corps throughout the 1950s and 1960s.