I ordered these for use in my boat but didn't install them because I made the mistake of ordering instant contact when I needed the switches to operate continuously.I chose the switches because they were described as fairly reliable and what I got was exactly as described.At 12mm the button is a bit difficult to operate and I would recommend a raised button for these Recommend size. I bought a serviced 16mm contact switch, it's easier to use and well built. I expect it will work well enough for my application. Comes with clear instructions with illustrations.