bayer animal health seresto flea tick 7-8 month collar for small dogs up to 18lbs bayer animal health seresto for dogs kills and repels fleas and ticks for 8 months in an easy-to-use, odorless, non-greasy collar. with bayer's innovative sustained release technology, this revolutionary collar offers hassle-free, continuous protection from fleas and ticks. seresto is a unique polymer matrix collar that offers a continuous supply of two active ingredients: imidacloprid and flumethrin for effective 8-month protection against fleas and ticks. that's one convenient, non-greasy, odorless flea and tick collar instead of 8 monthly treatments. the active ingredients are stored within the collar. they are released in low concentrations and are distributed over your dog's hair and skin surface. as active ingredients wear off over time, the seresto flea collar for dogs continuously replenishes the skin and hair coat with a new supply of active ingredients. in fact, fleas and ticks are killed through mere contact (no biting required).