Grenade - No 36M Mk. I INERT. Mills bomb is the popular name for a series of prominent British hand grenades. They were the first modern fragmentation grenades in the world. The Mills bomb was adopted by the British Army as its standard hand grenade in 1915, and designated as the No. 5. The Mills bomb underwent numerous modifications. The final variation of the Mills bomb, the No. 36M, was specially designed and waterproofed with shellac for use initially in the hot climate of Mesopotamia in 1917, but remained in production for many years. By 1918 the No. 5 and No. 23 were declared obsolete and the No. 36 (but not the 36M) followed in 1932. The Mills was a classic design; a grooved cast iron "pineapple" with a central striker held by a close hand lever and secured with a pin. According to Mills' notes the casing was grooved to make it easier to grip and not as an aid to fragmentation, and in practice it has been demonstrated that it does not shatter along the segmented lines. The Mills was a defensive grenade: after throwing the user had to take cover immediately. A competent thrower could manage 15 metres with reasonable accuracy, but the grenade could throw lethal fragments farther than this. The No. 36M Mk.I remained the standard grenade of the British Armed Forces and was manufactured in the UK until 1972, when it was completely replaced by the L2 series. The 36M remained in service in some parts of the world such as India and Pakistan, where it was manufactured until the early 1980s.