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 (49 feet) with reasonable accuracy, but the grenade could throw lethal fragments farther than this. The British Home Guard were instructed that throwing range of the No. 36 was about 30 yards with a danger area of about 100 yds.At first the grenade was fitted with a seven-second fuse, but during combat in the Battle of France in 1940 this delay proved too long—giving defenders time to escape the explosion, or even to throw the grenade back—and was reduced to four seconds.