This really does look like the mines from World War II when they are trying to hit the submarines. Its a very useful product to use when you are building or fixing computers or you want a light in thos very compact places. For $7 each I would get a couple of them.

The funny idea they post on boing boing is if you need to infiltrate a building just turn it on and hurl a few into the room and things might be illuminated.

Link: BBGadgets