Hanging bell comes with snap to make it easy to hang on any type of door knob. Great training device - dog rings bells that hang from door knob to let you know he/she needs to go outside. Instead of scratching, barking, and whining, train your puppy to jingle the potty bells. Made of durable nylon material for the rope, and strong metals that make the ringing sound not only loud, but unique as well. This rivet snaps around your doorknob to give your bells extra security when closing around your doorknob so that your dog cannot pull it off the door easily.