Mills Bomb
 
Here is a little but of equipment I was given recently, and I am pleased to confirm it is a drill (training) example, without a fuse and no explosive filling, plus you can see some holes drilled into it to make it clear it is a training example.  The classic Mills Bomb, a British Hand Grenade, where the steel casing is designed to be blown apart into the shrapnel caused by the grid around the casing, a devastating little close-quarter weapon, especially in the confines of a house or a bunker.
 
Designed by William Mills, this went into production in Birmingham in 1915.  It remained the standard hand grenade of the British Army up into the 1970s.  Only minor design changes were made during that time, and it was the classic 'pineapple'.  Fuses were originally 7 seconds though that was later changed to 4.