(Bayer) The performance you expect from topicals, in a collar! The Seresto Flea and Tick Collar provides 8 months of prevention and treatment against fleas and ticks for cats and kittens 10 weeks of age and older. Contains 4.5% flumethrin and 10% imidacloprid. The Seresto Collar's unique polymer matrix ensures that active ingredients are released slowly and continuously in low concentrations. Collar should be worn continuously; no need to remove for bathing.