Hartz Ultraguard Flea & Tick Collars for Dogs and Cats Fresh scented Kills and repels fleas, ticks, flea eggs and flea larvae, plus prevents flea eggs from hatching for 7 months. Can be worn simultaneously with your cat's regular collar Water-resistant design won't cause loss of effectiveness if your favorite feline takes a stroll in the rain Features a breakaway, safety release snap For use on adult cats and kittens 12 weeks of age and older