United States hand grenades

The military of the United States has used many different types of hand grenades since its foundation. == High explosive, fragmentation, and blast == === Mk I === The Mk 1 grenade was introduced in 1917 during World War I. A multistep arming process on the device resulted in many failures, and as a result it was replaced in 1918 by the Mk II. === Mk II and Mk IIA1 === More commonly known as the Pineapple, the Mk II series (also written Mk 2) was the most commonly used US fragmentation grenade of the Second World War.

Source: Wikipedia — United States hand grenades (CC BY-SA 4.0)