Pet Armor Plus Igr For Dogs Flea And Tick, Size: 89-132lb 3 Count Box 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.