ZoGuard Plus For Cats protects cats from the dangerous effects of fleas and ticks. Contains fipronil and (S)-methoprene. Fipronil is the top active ingredient available for control of fleas and ticks. (S)-methoprene breaks the flea lifecycle by preventing flea eggs and larvae from maturing. Kills fleas, ticks, chewing lice, flea eggs, flea larvae, and prevents flea pupae development. Kills ticks for up to 1 month including those that may transmit Lyme disease. Controls mites that may cause sarcoptic mange. Fast-acting and long-lasting. Waterproof. (3) 30 day treatments per box.