K9 Advantix® II is a once-a-month topical flea, tick, and mosquito treatment for dogs and puppies 7 weeks of age and older. It contains imidacloprid and permethrin. It is available in 4 dosage sizes: 10 lbs. and under, 11-20 lbs., 21-55 lbs., and dogs weighing over 55 pounds. It is available in both 4 packs and 6 packs. Nothing else offers this kind of protection against biting fleas, ticks and mosquitoes. Packs sold individually.