Anti theft design: beautiful appearance, absolutely strong anti-theft. Stop worrying about bad guys stealing your doorbell Compatible doorbell: anti-theft video doorbell base for video doorbell (generation 1-4) and video doorbell (to be released in 2020). The size of doorbell that can be placed inside shall not exceed 2.55 inches wide x 5.11 inches high x 1.14 inches deep. (The doorbell is not included in the package) Compatible door: applicable to most types of doors. The thickness of the door must be between 0.6 inches and 2.3 inches. You can measure the thickness of the door before ordering. It can be used for left or right door opening. (Doors that must be opened inwards ) Easy to install: It is very easy to place the video doorbell in the housing and adjust the fixing clip according to the thickness of the door Installation instructions and various parts are included in the package. The bracket has a unique function. The distance between the doorbell and the door can be adjusted by sliding on the bracket Including: 1 * anti-theft video doorbell base.