Kwik-Shot Soot Stopper, 3 oz. Toss-In Canister (3-Pack) Easy to use: place pre-measured, toss-in canister on a hot bed of coals that has been burning for at least 15-20 minutes For a safe, efficient fireplace, have your chimney professionally cleaned on a regular basis Canisters are made of safe-to-burn material and turn to ash in the fire Package contains three (3) cartridges Heat activated at 265F