(Bayer) Advantage II for Dogs is a once-a-month topical flea prevention for dogs and puppies over 7 weeks old. Contains Imidacloprid, an adulticide, and Pyriproxyfen, an insect growth regulator. Advantage II for Dogs controls existing flea infestations on your dog and prevents further infestations. Kills all flea life stages. Kills fleas within 12 hours of application. Prevents further infestations for up to 4 weeks. Waterproof.