The Seresto Flea Tick Collar 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 for 8 months. As active ingredients wear off over time, Seresto for dogs continuously replenishes the skin and coat with a new supply of active ingredients. Fleas and ticks are killed through contact with the active ingredients — no biting required. *Seresto is water resistant and remains effective following a shampoo treatment, swimming or after exposure to rain or sunlight. Under normal conditions, effectiveness lasts for 8 months. In order to maintain an 8-month duration, dogs must not be bathed more than once per month. For dogs that swim once a month or more, the control duration is reduced to five months for flea control, and reduced to seven months for tick control.