SM-226L-3Q Seco-Larm Overhead Door Mount N.C. Magnetic Contact w/ 3 Wires for N.O./N.C. Applications (One Pack)

I have not installed this yet but I have tested it. It appears well made and functions as I expected it to. This switch has the ability to control two functions with NO and NC positions. I plan to use this for my garage door to tell if it open or closed (we have been known to leave the door open all night). The two contacts will let me have a red light if the door is open and a green light if it is closed without using a relay in my DIY indicator panel. This also lets me know of any faults because one light will always be on. That makes for the minimum of circuitry in the panel. I also found a magnetic switch with the same function for the man door.

So, 5 stars for quality, but yikes, $20 for a magnet sensor, so 4 stars for value. Anyway, I bought a Nexx garage door wifi control which is just a repurposed $5 Sonoff control with a very cheap magnetic sensor for reporting door position, but it also has a fairly good app (so you pay for the app I guess). Read the reviews on the Nexx, a large number talk about it working and then not, becaue the position sensor stops reporting correctly. and thats because It needs an 1/8 gap on a garage door. On my wobbly old door youre never going to get that consistency; so Sentrol to the rescue with their 2 inch gap. This sensor is industrial quality. Buy a LeMotech ABS Plastic Dustproof Waterproof IP55 Junction Box, cut the cord on the cheap magnet, and splice it into the Sentrol inside this box. Two day shipping, problem solved. Oh, and use the black and green wires from the Sentrol for this application.

Magnet bracket works fine on probably 90% of garage doors. Mine, unfortunately was in the 10%. Had to rig up a method to attach the bracket. Would be nice if the bracket was more a of C shape rather than an L shape.

Just what I needed for my barn roll-up door. Well pleased with all phases of my purchase.

Works great if you do better than me and wire it correctly the first time. Thanks to whoever put the following out there: When the door is closed, there is continuity between Black/Green When the door is open, there is continuity between Black/Red

Very durable. Utilized for double garage doors to detect (open/close) positions. Connected reed switches in series to controller to operate and monitor garage door utilizing WiFi.

Needed for a normally open circuit on a gate alarm . Works fine . Just installed so dont know how long it will last but looks well sealed from moisture. Looks like a good product

Works as expected. Used it to automate my garage door with a Raspberry Pi. Now garage door knows position when I give the command to open or close vs just actuate.

I wish I had found this years ago. This works perfectly on the top edge of my garage door

I have 2 of these installed on garage doors, unheated space for many years and they have never failed in harsh MN weather, that is why I purchased 2 more for barn doors on a new building.