Amazon.com: 4 Pack Window Door Alarm, Door Sensor Alarm for Kids Safety, Alarm System for Home Security with No Batteries for Pool, Garage, Apartment, Dorm, RV and Office : Electronics
ECHO (NaK) Series - Azurr-Technology, s.r.o.
Using a Raspberry Pi distance sensor (ultrasonic sensor HC-SR04)
ECHO alarm, s.r.o. • Mapy.cz
Amazon.com: 4 Pack Window Door Alarm, Door Sensor Alarm for Kids Safety, Alarm System for Home Security with No Batteries for Pool, Garage, Apartment, Dorm, RV and Office : Electronics