Sonoff SenseGuard DW Gen2 Zigbee Door & Window Sensor | SNZB-04PR2

This is the second generation of Sonoff’s door and window sensor, and the changes are the practical kind. The transmitter is 13.5 mm thick and weighs 45 grams, so it sits on a frame without getting in the way or looking like security equipment.

It tells you when a door or window opens and closes. On its own that is a log; combined with other devices it becomes useful – a camera that starts recording, a gateway that sounds an alarm, lights that come on when you open the front door at night.

The new part is tamper detection. If someone pulls the sensor off the frame or damages it, you get an alert immediately, instead of the sensor simply going quiet.

It also saves energy. Link it to your air conditioner or heater so they stop while a window is open, which in a Lebanese summer is the difference between cooling a room and cooling the street.

It mounts horizontally or vertically, tolerates a gap of up to 30 mm, and the magnet detaches – so awkward frames, thick frames and uneven windows are all workable. Standard AAA batteries last up to three years and cost nothing to replace.