Smoke bomb to control nuisance burrowing animals. Emits thick suffocating smoke into animal burrows. Works on gophers, moles, woodchuck, rats, skunks and underground squirrels. Eliminates the threat of secondary poisoning. Use outdoors only. 4-pack. Active Ingredients: 39.4% Sulfur, 38.8% Potassium Nitrate, 9.3% Charcoal Carbon, 12.5% Inert Ingredients.