Liberty 50® provides long-lasting flea and tick control. When you apply Liberty 50, permethrin, the active ingredient, is stored in the oil glands under your pet’s skin. It is then distributed continuously to the skin and hair of your pet through the hair follicles. Liberty 50 also contains Nylar insect growth regulator, which is the best quality IGR for your pet sold in the USA. Nylar is purported to bind to hair and skin, maintaining effectiveness even when dogs get wet.