Casey, Trias, and ibm all were mostly correct. This is the guts of an "offensive" anti-personnel grenade. Ya, ya, all grenades are offensive to their targets. In milspeak, an "offensive" grenade is one designed to be tossed by a fellow who might not be able to take cover from it's effects, such as an attacking soldier, so those effects are minimized, both blast and long-range fragmentation. Defensive grenades are presumed to be thrown from cover, and hence are designed to have greater local and longer-range effects.

The whatzis are the guts of an unidentified euro version, which would have a plastic outer casing. The interior sphere is aluminum, and the ball bearings/bb's are glued to that shell.

The body of the US egg grenade on the right is included for scale purposes, the fuze in the grenade on the left is from the one on the right - vets will recognize a training fuze from the light blue spoon. Well done - you guys really did pretty well - but would do well to heed JTG's warning about me, too. [/evil smirk]

Here's your next challenge. Ready? Set? Go!