|M34 White phosphorus hand grenade.
This is an inert shell that, if active, would be filled with 15 ounces of white phosphorus and a small charge that distributes it over a 35 meter radius when set off. Anyone in that area without protection would be severely burned and/or poisoned, and flammable material would likely end up in flames. Interestingly, the average soldier is said to be able to throw it approximately 30 meters, 5 meters short of its radius of destruction. Much larger white phosphorus incendiary bombs were used in WWII and probably still are: Compared to them this is just a baby.
Interestingly, descriptions you can find on the web say this grenade, which is considered an obsolete design, can also be used to create a smoke screen or signal. The smoke created is phosphorus pentoxide, which is actually not particularly toxic, and it's said that the high temperature at which the white phosphorus is burning causes the smoke to rise rapidly, making it more suitable for signaling purposes than for creating a smoke screen.
Source: eBay seller finch34
Contributor: Theodore Gray
Acquired: 20 October, 2005