Hang this bell system on the inside of the door that your pet typically exits your house from and your dog will learn to nudge them when he is ready to go outside, letting you know it is time. Four bells on each Poochie-Bells unit allows you to easily hear them ring, but not so loud that they are overbearing. Made in the USA. 25" long. The Doggie Door Bell Hooks are a decorative way to hang your Poochie-Bell, leash, or keys. Hooks attach securely to a wall or door. Ideal for hanging the Poochie Bell on a wall so you it doesn't jingle every time you open the door. Each hook measures 2" x 1 1/2". Installation screws included.