Do an Amazon search of "SadoTech Wireless Doorbell" which shows all the combinations available with this door bell. Model CXR has 2 receivers and one button for $39.99. Model CX has 1 receiver and 2 buttons for $35.99.
I got these instructions from SadoTech directly. I have suggested to SadoTech that these notes be included with the door chime. They also have a video guide that they can send you. However, removal of the circuit board is not demonstrated clearly. Note: You will need a teeny tiny screwdriver, like for eyeglass repairs, for the screws on the circuit board.
1) Upon removing the button cover you will see the circuit board and two small screws holding it in place.
2) Remove these two screws by unscrewing it from the circuit board.
3) Then wiggle the circuit board out of the button case.
4) You will see the back of the button with bare plastic and hole guides for the new screws you will use.
5) To use the supplied screws, drill a starter hole into plastic case and into your desired location.
6) Then screw in tightly the button case to your location
7) After this, then place the circuit board back in and screw it back on.
8) Apply the button cover and you should now be good to go!
The doorbell is made of plastic and is meant to be placed in a covered area where it is not exposed to rain, water or snow. There are two pieces that unsnap and snap together when the battery needs replacing, so there are non sealed areas that if exposed to liquids could damage the internal components.