Revolution for cats. Action: kills fleas, flea eggs & larvae, plus heartworm, roundworm, hookworm & ear mites. Apply monthly. How to use: apply contents of squeeze tube directly onto skin at the back of the neck. For cats over 6 weeks of age. Formulation is non-greasy & is water safe after 2 hours Prevention of Heartworm Disease in Cats. Note Cats should be tested Adult Heartworm Clear before giving this medication. Highly recommended.