Roller Ball Recessed Button Pressure Reed Switch - Window/Door Alarm Contact Sensor Plunger with Terminals

We just installed this today on the inside track of a sliding door as an alarm contact and it works perfectly as described.

This is just like 4 other switches I own for use in alarm systems, what I thought I was buying was a door light switch? The third terminal is for an end of line resistor required for all CMOS input alarm systems, not a normally open when closed door switch.

The item resolved issue with our alarm system when the wires were inadvertently cut during a construction project. The new button reconnected the alarm.

Good, cheap switch

It was easy to replace the nonfunctioning alarm sensor in our home.

Works great. Easy to install.

Bought a similar sensor a month or so ago that started hanging up after a week. It was a plunger style sensor. This rollerball has been installed for 2 weeks now with zero issue. Would definitely recommend this over similar models.

Don't be fooled by the NO label on the contact. I put my meter on it and it gave me a short when the ball was pressed...I was looking for a switch that gave me a short in the open position.