These switches are EXCELLENT! They are constructed with high-strength plastics and mechanically they are VERY solid. I don't see how they could wear out even if used hundreds of times a day for decades.There are three connectors on the back that are mounted solid - basically an extension of the whole switch. Nothing loose back there at all. One of the connectors is gold-ish in color and must be connected to ground so that the LED lights up when the switch is turned on.For those interested in the tolerance specs, I decided to sacrifice one of these to see just how many volts the LED would tolerate and was pleasantly surprised with the results.First of all, these are rated at 20 amps. HOWEVER, I would NOT run 20 amps through these at 12 volts. That's 240 watts and if you can imagine the kind of heat you might get from 240 watt light bulb - you wouldn't get that kind of heat concentrated in this switch, but from the looks of everything, I believe the switch would most definitely get warm if not hot at that kind of amperage. And of course, if the switch needs to sustain 20 amps at 12 volts, then you should be looking at a 25 amp rated switch AT A MINIMUM, so I would say it would be safe to use this switch at 10 amps but not more than 15 - TO BE SAFE!SO, in my testing, using a bench power supply, the LED starts turning on at around 2.5 volts and starts getting close to max brightness at around 5 volts, though it does get about 15% brighter between 5 and 12 volts and it gets no brighter above 12 volts.As I continued to increase the voltage, the LED didn't flinch until I got past 45 volts, and at 50 volts, I fried the current limiting resistor attached to the LED. I had my bench power supply set to max amperage at 5 amps, yet this LED hung in there to where the resistor fried before the LED ever got hot enough to burn out. In the photo, the LED is sticking up but it was folded over, laying on its side next to the resistor. I moved it to get a good photo of the burnt resistor.I would say that as long as you keep your wattage under 200 watts, you could use this switch at any voltage up to whatever voltage calculated out to be 200 watts (take the voltage times the current to calculate wattage).After I fried it, I took some pictures so you can see what's inside these things. Very basic ... one LED and one current limiting resistor and a design that is top-notch with a very solid build. These things are NOT waterproof so I would not use them in any application where they might get wet, but they would be perfectly fine in any application where they are only exposed to open air (or in a vacuum I suppose). They have a solid click feel to them and they look very professional.I haven't measured around the inside of the ring yet, but if the hole was drilled to the right size and the material you're mounting them to isn't too thick, they will push in and click tight against the mounting plane and they will hold that position very well.My only complaint about the company is that they included an insert with a QR code that said to scan it for a surprise, free gift. When I scanned it, it took me to the warranty registration page on their website. Once I registered it (and provided a screenshot of the order details along with a photo of the UPC code on the package, plus my name, email address, and phone number), I was not offered any gift at all.I certainly understand that companies want feedback from their customers and warranty registration is a good thing for a manufacturer, but manipulating people into registering their product by promising them something and not delivering on that promise is just bad ethics. Don't offer a gift if you don't intend on giving one and let people decide for themselves if they want to register the product warranty or not without manipulating them with a lie in order to get them to do it.Overall - for this price, these are amazing switches. I highly recommend them and will purchase these again if I ever need any.