4 Sets NC Wired Door Alarm Magnetic Contact Sensor with Double Side Tape

Good

I've had an alarm monitoring company for years. A magnetic sensor became brittle and cracked. The company would not send a replacement without a tech to come out for $120. These screwed right into the spot and we were back in service instantly.

Used these to replace old door contacts after a new door install. The contact distance is nice. Almost 1/2" of distance for them to work.

Best price and timely delivery however due to my own mistake it is not what I need for my windows/patio door.

I somehow thought this set came with the alarm, but they didn't. That is why it only gets 3 stars from me because I can't test them out.

I saved $250 and did not have to use an alarm company to replace broken ones

This is a four-pack of reed switches designed to determine if a door or window is open or closed. Reed switches like this are available in several styles; this one is a plastic rectangle with double-sided sticky tape that sticks visibly to the door frame and the back of the door. One side is a magnet, and the other side is a sensor. It's a less polished look than the circular kind that drill into the door frame, but it's also substantially easier to install and set up.This pack takes the ease of installation a step further with screw terminals for the sensor side, so you don't have to figure out how to hide a wire splice nearby - you can just pull the actual alarm wire all the way to the sensor and wire it in with a screwdriver. I recommend covering the connections with a little bit of hot glue to hold them in place once you're finished to prevent them from accidentally getting pulled or damaged.My experience is that most reed switches like this are pretty equivalent. The read range was exactly as expected, and I didn't have problems with any of the four sensors when I installed them. No complaints, and I'd reorder this product next time I need more.