Red Smoke Flare

The Red Smoke Flare item is a pyrotechnic device used primarily to mark a location by placing a red smoke column object on the terrain.

Some uses that people have come up with:
 * marking locations for raids
 * smoke bomb the Flag Rooms in the Warsong Gulch battleground
 * props for floor shows and fashion shows

Source
This item can be purchased for from  in Blade's Edge Mountains, in limited quantities.

The Red Smoke Flare item does not bind, and can be bought and sold at the Auction House.