Home security DIYers, this OC-55 reed switch is exactly what you need for reliable door and window monitoring! The zinc alloy construction feels solid and durable - not some flimsy plastic sensor that'll break easily. What's really handy is the NC/NO functionality - you can wire it as normally closed or normally open depending on your alarm system requirements. The 25cm cable gives you plenty of wiring flexibility, and the surface screw mounting makes installation straightforward on wood, metal, or UPVC surfaces. I've installed these on my garage doors and basement windows, and they've been rock-solid reliable through temperature changes and daily use. The triggering range of 40-50mm means you don't have to be super precise with magnet placement, which makes installation much easier. The silver gray color blends discreetly with most door frames, and the compact size (about 1.26 inches) doesn't stand out obtrusively. These work perfectly with most burglar alarm systems and access control setups - just remember they provide a switch signal rather than directly handling power. For the price, the quality is impressive, and having that 90-day guarantee gives you peace of mind. If you're setting up a basic security system or need reliable sensors for monitoring doors and windows, these magnetic contact switches deliver professional performance at a very reasonable cost. They've become an essential part of my home security setup!
Free 30-day returns 
Free 30-day returns
