Potty Training Bells Red Paws 31"Potty Training Bells Red Paws 31" Coastal's Advanced Dog Potty Training Bells it easy to train your dog to go outside without scratching, whining, or barking. Two snaps allow for 27" or 31" lengths to accommodate most doors and sizes of dogs. Available in solid black and patterns, these potty training bells are both fashionable and functional options for teaching your dog to let you know when they need to be let out.