ChunHee Smart Dog Door Bell Wireless Puppy DoorBell for Potty Training, Dog Bells to go Outside, Bells for Dogs to Ring to go Potty, 2 Dog Buttons. Touch Sensitive dog doorbell:ChunHee smart dog training bells for door responds to a gentle touch，especially suitable for puppy bells for door potty training.large and sensitive touch area making it suitable for dogs of all sizes.
eBay