Dog Doorbells Simply hang over any door knob Keeps your Dog from scratching the door frame when they want to go in or out. Comes in 3 colors, Black, Red, Blue. We ship the colors out randomly, If you want a particular color, please leave us a note when you place your order. Simple and super effective way to teach your Dog to communicate: a.) When it wants to go outside, or, b.) When it wants, in or out, of a closed interior door. [Can also be used to teach them to ask for Food.] Beautiful, Loud, Pleasant sounding Bells Height Adjustable (2 Positions) Won't damage wood work USA SELLER Fast Same Day, or Next Business Day Handling [ no waiting 2 months for your items from China ]