Product ColorBlack Material: Nylon + Iron Size: Strap Length: 2.5*96cm, Bell Diameter: 3.8cm Package Included: 2 x Pet Bell Rope br/1. Useful and Simple Pet Doorbell: These dog bells can be easily hung on the doorknob or handle. Without scratching or barking, this bell will know when your pup needs the toilet. 2. High Quality Puppy Doorbell: The dog doorbells are made of strong nylon strap and durable iron bell, bite-resistant, suitable for long-term use. Besides, this adjustable doorbell strap has 7 bells, which can be easily touched by most dogs. 3. Acoustic Sound: The dog doorbells voice is loud but not harsh and can be heard within 20 meters. That way you cant hear the sounds in the same room, you dont have to worry about the dogs sneaking out. This funny dog bell will catch your attention. 4. AdjustbaleThis design gives you length adjustments compared to traditional dual length bells. This allows for easy adjustment of the length at the bottom of the door or wall based on your dogs size or the height of your door. 5. VERSATILE DESIGNYou dont have to worry about the dog doorbell cord not matching your doors or knobs in type or size because these dog training door bells are designed to fit all kinds of knobs. These are the ideal bells for dogs to ring to get out.