I have purchased several wireless doorbells for my projects, including of course, wireless doorbells. Pros: 1) they work. 2) like units (receivers) can be programmed to respond to different buttons (transmitters) as required 3) inexpensive 4) receivers with lights assist hearing impaired people 5) easy to mount (or hang) 6) Seller (to date) is 100 per cent reliable 7) battery life in transmitter i...