Revolution is a monthly topical treatment manufactured by Pfizer that protects cats against various internal and external parasites like fleas, roundworms, hookworms, heartworms, and ear mites. It works by killing all stages of the flea life cycle and uses the active ingredient selamectin, which causes neuromuscular paralysis in parasites. Revolution comes in separate packs for kittens and cats depending on their weight and is applied to the skin at the base of the skull once a month to maintain effective parasite control. It is a safe treatment option for breeding cats, pregnant cats, and nursing mothers.