Peppermint Flea & Tick Collar offers an effective, convenient way to repel fleas and ticks up to 4 months and mosquitoes up to 1 month. Helps prevent infestations. Powered by nature and proven to work. Collar comes in 1 size for dogs (fits up to 23" neck) and cats (fits up to 13" neck). For dogs and cats 4 months or older.