4. When the measured distance is less than the set distance, the buzzer alarm 1. Use high-quality materials with guaranteed quality 3. The alarm distance can be set. After pressing the setting button, you can the plus or minus keys to modify the alarm distance, and it has the function of saving after power failure 2. The ultrasonic distance measuring instrument of single chip microcomputer is designed with single chip microcomputer+-SR04 ultrasonic sensor+Nixie tube+button+buzzer 5. The characteristics of this design: wide measurement range, stability, and very convenient operation. It can be used when powered on, Weight: 0.18298367746 Pounds, Manufacturer: Suoumwa