ZODIAC SPOT ON II FLEA CONTROL FOR CATS AND KITTENS provides relief from flea infestation for up to 4 weeks by killing flea eggs laid on your pet, thereby, effectively breaking the flea life cycle. Adult fleas spend virtually all of their time on the pet and produce vast numbers of eggs that drop off the pet and develop in the environment. ZODIAC SPOT ON II FLEA CONTROL SOLUTIONS FOR CATS AND KITTENS is designed to kill flea eggs, thereby breaking the flea life cycle. Kills flea eggs before they hatch Remains effective for up to 4 weeks Easy to use Spreads over complete body through natural motion of animal Do not use on cats or kittens under 12 weeks of age 4 Month Supply (4 tubes x 1 mL each) Active Ingredient: (S)-Methoprene 3.6%