2X Magnetic Reed Switch Normally Open Closed NC NO Door Alarm Window Security/Magnetic Door Switch/Magnetic Contact Switch/Reed Switch,DC 3V to 12v Lamp（White）

Only one of the two worked. One was shipped broken.

I purchased this to make my own wired open/close detector for my garage door opener. The ability to use this both as a Normally Open or Normally Closed switch is great because I wasn't sure what mode I needed to have for my plan to work. So far it has worked flawlessly for me.

I found this magnetic switch and it was more-or-less perfect for my application, but I couldn't help but notice all of the reviews of melted units. On further inspection you'll notice that many of these reviews detail misuse of the product by passing far too much current through it, for example to a lightbulb. This item uses a lightbulb as an example but explicitly says it should run to some sort of panel. This is a switch meant for powering a relay that can actually handle the current of your application. This is a switch for a signal, not for power. This will work great for something like an Arduino, but it will not for powering truck lights. Be warned that this is totally a Chinese wholesale product and you probably cannot pass through as much current as it says, but using it modestly will yield the intended result. Realistically you should not pass through 0.5A. You don't need much for a signal.

I use this switch with warning lights on my garage door. I install a 120v to 12v transformer in my garage next to my garage door opener. Then install two 12v lights in my room connected to my garage. When my garage door is open, the lights are on. When it is closed, they are off. I can always tell if I forget to close my garage door.

Purchased to use with a small strip of LED lights for our RV pantry door. Lights turn on when door opened and turn off when door closed. Worked great for two weeks then failed. You can see it melted and was very warm to the touch when I removed it. See how long this second one lasts but these are very cheap. Buy something better. I bet I only had less than a 10w load on it.

If you are using these for doing fun little projects, these are great little reed switches. If you are wanting to use them to notify you of a window or door opening to trigger a home alarm or some other automation, these are simply not good enough. I originally bought these to alert me when my shop bay doors were open, but they just weren't strong enough to give me what I was looking for. I ended up going with some beefy industrial reed sensors for that project and they are still working a year or more later. I still keep these little reed switches around to play around with other home automation ideas and they work great for proof of concept type projects.

So inexpensive and such a difference. Installs in fifteen minutes and transforms your closet experience. Turns light on when you open and off when closed. Very flexible installation and ease of use! Love them!

Installed a light under my truck bed cover that uses this as an activation switch like a refrigerator door light. Works great, but the magnet wasn't big enough for my application. I found a bigger magnet in the garage, now I have no problems.