Adams Plus Flea & Tick Collar For Dogs, Waterproof collar provides flea and tick protection for dogs and puppies 12 wks and older. Kills fleas, flea eggs, flea larvae and ticks, including those carrying Lyme disease, for up to 5 mos. Features Precor Insect Growth Regulator to break the flea life cycle and prevent reinfestation. Contains 10% propoxur. Small fits dog necks up to 15"; large up to 25".