The Adams Flea and Tick Control Collar for Dogs kills adult fleas, ticks, flea eggs and flea larvae for up to 7 months. It prevents infestation by breaking the flea life cycle. The active ingredients work their way to the surface of the collar and is rubbed onto the fur of the animal. The active ingredients move through the oils and from hair to hair to cover the entire body and works even when wet. This collar can be fitted for all dogs with necks up to 26″.