Kills fleas through contact, so fleas don"t need to bite to die. * Kills fleas within 12 hours of initial application. * Long lasting, as it continues to kill fleas and ticks all month long. * Approved for use on puppies and kittens 8 weeks of age and older and on breeding, pregnant or lactating cats and dogs. * Waterproof: effective even after swimming, bathing and grooming.