I ordered these to use on my boat but did not install them due to the mistake of ordering instant contact when I needed permanent action switches. 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 tricky to use and I would recommend a raised button for this size. I bought a serviced 16mm contact switch, it's easier to use and well built. I assume it works well enough for my application. Comes with clear instructions with illustrations.