The Adams Flea and Tick Collar for Dogs and Puppies kills adult fleas and ticks for up to 6 months of protection. Two collars provide up to 12 months protection against ticks, fleas and mosquitoes. It repels mosquito bites for up to six months. 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. One size fits all. Water Resistant.