Ground Illumination flares are, as I understand, contained within a canister. Turning the bottom and striking it against a flat surface ignites a charge which lifts a flare into the air. The flare is then suspended by a parachute for some minutes while it illuminates the vicinity.
I was going to use these for an airsoft game me and my friends are going to up north. The owner of the field has okayed the use of the flares, and his plot of land is large and remote enough to remove the chance of creating any undue alarm. Besides, the neighbors there are into the games and send their husbands and sons to play.