AN-M8 smoke grenade

The AN-M8 HC Smoke Grenade designated as the Army/Navy Model 8 HC Smoke Grenade (AN-M8 Smoke HC) is a US military grenade used as a ground-to-ground obscuring or screening device or a ground-to-air signaling or target-marking device. 
History.
Developed in the 1940s, using a sheet-steel cylinder body that can emit a dense cloud of white smoke that would last from 105 to 150 seconds.
The AN-M8 was used extensively by American or other allied forces used throughout World War II to the 1990s. As of the September 2000 version of FM 3-23.30 "Grenades and Pyrotechnic Signals", the AN/M8 was listed as obsolete.
Details.
It is used for smoke screening, target marking, and signalling, although the M18 colored smoke grenades are mainly used for the latter.
Field Instructional Use.
"When employing the M18 or AN-M8 HC hand grenade, it may be desirable to use one of these grenades without the fuze. To do this", the following procedure should be used in combat only: 
Toxicity.
The HC smoke of the M8 is more toxic than that of the M18 grenade. The fumes comprise an acidic smoke of zinc chloride (ZnCl2), which produces hydrochloric acid on contact with water.