Multiple uses: the bells are suitable for dogs of all sizes. Dog training: Potty train using simple repetitions. High decibels: The bell can be heard clearly within a radius of 26 meters to remind the dog owner to open the door to prevent damage. Anti-bite: nylon rope with adjustable buttons and iron bell to prevent dogs from tearing it off. Easy to install: The item can be easily hung on all types of door handles or hooks near the door.