Bundle includes 3 plant-powered collars that each repel feas and ticks for up to 4 months. A year’s worth of added protection. Powered by nature and proven to work, collar comes in 1 size for dogs (fits up to 21" neck) and cats (fits up to 13" neck). For dogs and cats 4 months or older. Active issue? Collar doesn't kill bugs. Use Flea & Tick sprays for pets, home and yard as directed.