K9 Advantix II 4-Pack Tick Control Topical Prevention & Treatment, suitable for Large Dogs and puppies 7 weeks of age and older, weighing 21-55 lb. This veterinarian-recommended monthly flea, tick, and mosquito treatment kills through contact, eliminating the need for biting. Waterproof and easy to use, it provides up to 30 days of protection, even after bathing or swimming. Contains four 1-month applications.