PetLock Plus is a monthly topical flea and tick preventative for dogs and cats. PetLock Plus kills 100% of adult fleas on your pet within 18 hours and 100% of all ticks within 48 hours. PetLock Plus contains an insect growth regulator, S-Methoprene, which kills flea eggs and larvae. It’s effective against all stages of the Brown dog tick, the American dog tick, the Lone-Star tick and the Deer tick (the major carrier of Lyme disease). PetLock Plus remains waterproof for 30 days.