Wireless Magnetic Reed Switch - LS-321-F1 | Longsin Intelligence
Magnetic contact switch (door sensor) : ID 375 : $3.95 : Adafruit Industries, Unique & fun DIY electronics and kits
BOSCH, Radion Series, Wireless reed switch, For doors/windows, Surface mount, Suits RFRC-STR2, RF3212E, B810
Amazon.com: 5Sets Magnetic Reed Switch, Magnetic Door Switch/Magnetic Contact Switch/Normally Open Closed NC NO Door Alarm Window Security, for DC 5V 12V 24V Light (Black-B31) : Industrial & Scientific
How does Reed Switch work? | Deeter Electronics - Reed Switches
Netvox Window/Door Sensor and Wireless Glass Sensor - ThingPark Market