This magnetic door and window sensor is probably the smallest sensor in the world.
Its size is only 3.5 x 3.5 x 2 cm (1.4 x 1.4 x 0.8 inch).
The magnetic sensor sends wireless information when the door/window is opened or closed. The signal is sent up to 40 m (130 ft) distance directly to your Android smartphone (iPhone app under development) and the DST connector.
The button battery (CR2430) lasts up to 3 years and is replaceable. Installation is through a special (removable) sticker on any flat surface.
Scope of delivery:
1 x Magnet Door/Window Sensor
1 x button battery (CR2430)