The Strikeback Flea Killing Fogger is supplied in a 2-pack, as a minimum of two are often needed to treat a room. Foggers simply fill a room with an insecticidal smoke that fleas cannot avoid, providing the perfect way to achieve an immediate control of fleas. Strikeback Flea Killing Fogger smoke is light and distributes evenly throughout a room far more effectively than aerosol foggers, which project a heavy water based mist that falls quickly onto the floor. Contains: Permethrin 13.25% w/w Always read the label and product information before use. Use biocides safely.