It was internally fragmented and incorporated a cast-iron body.

To light the grenade, the user had to remove a covering that was on the fuse, then strike an external Brock matchhead igniter against the fuse.

15 had been created specifically for the Middle Eastern theatre of World War I, mostly for the fighting in the Dardanelles.

[3] However, there were a few problems; the explosive charge was too large, which created smaller-than-expected fragmentation when the grenade exploded.

In addition, it was considered too large because of its 3-inch (76 mm) circumference.

15 would be useful in breaching German defenses and trench clearing.

5 "Mills bomb" was running seriously behind planned figures, and not enough of them could be supplied before the start of the Loos campaign.

15 was beset with problems, in particular the wet conditions encountered made the fuse almost useless.

15s failed to ignite due to inoperative fuses.