PetLock II kills and controls all flea life stages. PetLock II for Dogs contains the same active ingredients used in Advantage II. PetLock II uses a waterproof, fragrance-free formula.PetLock II is a fast-acting solution. The product kills existing fleas within 12 hours. Reinfesting fleas are killed within 2 hours with protection against further flea infestations lasting for up to 4 weeks.