Broadline Spot On Solution for cats is a topical treatment providing broad-spectrum protection against both external parasites (fleas, ticks, lice, mites) and internal parasites (roundworms, hookworms, tapeworms, and sometimes lungworm and bladderworm). It's easy to apply as a spot-on to the back of the cat's neck. The active ingredients typically include Fipronil, (S)-methoprene, Eprinomectin, and Praziquantel. It is available in different strengths based on the cat's weight and is specifically for cats, not dogs.