display of the current distance to the obstacle, and with buzzer alarm function, it can be used as the reverse radars of the car, and the alarm distance can be set by the buttons, applicable to a variety of scenarios. Easy to Use: Simple operation, no programming required, can be used by simply plugging into the powersupply, no professional knowledge required. High-precise Distance Measurement: HC-SR04 high-precise module, built-in high-accurate distance measurement probe, stable distance measurement, measuring distance up to 4 meters, to meet most of the distance measurement needs. Real-time Display: Transistor-driven digital tube, the digital tube real-time display of the current distance to the obstacle, so that the user can real-time grasp the distance information. Alarm Function: Buzzer alarm function, when the distance is less than the alarm distance, an alarm sound is issued to remind the user to pay attention to increase safety. It can be used as the reverse radars of the car, and the alarm distance can be set by the buttons, applicable to a variety of scenarios. Specifications: Name: Distance Measuring Module Material: circuit board + parts Type: DIY Parts Set without housing, DIY Parts Set with housing (optional) Power supplying: 5VDC or 3 * AA battery (not included) Measuring ranges: 0.01-4.00m Printed circuit board size: 72 * 62mm / 2.83 * 2.44in With housing size: 89 * 77mm / 3.50 * 3.03in Package size: 100 * 100 * 80mm / 3.94 * 3.94 * 3.15in Package weight: DIY Parts Set without housing: 80g / 2.82ounce DIY Parts Set with housing: 132g / 4.66ounce Packing List (DIY Parts Set without housing): 1 * Distance Measuring Module OR Packing List (DIY Parts Set with housing): 1 * Distance Measuring Module 1 * Housing