Bayer K9 Advantix II 4 Pack Tick Control Topical Prevention & Treatment, designed for extra-large (XL) Dogs and puppies 7 weeks of age and older, weighing 56-100 lb. This veterinarian-recommended monthly flea, tick, and mosquito treatment kills through contact, eliminating the need for biting. Waterproof after 24 hours, it provides continuous protection for up to 30 days, even after bathing or swimming. Do not use on cats. Contains four 1-month applications.