Turns soote into a brushable ash in free-burning, non-airtight fireplaces, woodstoves, furnaces, and boilers. Makes chimney clenaing easier and reduces the danger of chimney fires. Safe to use with all types of chimneys. Heat activated at 265 degreeF. Place the pre-measured, toss-in canister onto a hot bed of coals that has been burning for at least 15-20 minutes. Most effective when used in non-air-controlled fires. 3-Pack per box.