This is the HC-SR04 ultrasonic distance sensor. This economical sensor provides 2cm to 400cm of non-contact measurement functionality with a ranging accuracy that can reach up to 3mm. Each HC-SR04 module includes an ultrasonic transmitter, a receiver and a control circuit. There are only four pins that you need to worry about on the HC-SR04: VCC (Power), Trig (Trigger), Echo (Receive), and GND (Ground). You will find this sensor very easy to set up and use for your next range-finding project! This sensor has additional control circuitry that can prevent inconsistent "bouncy" data depending on the application. https://elecena.pl/product/15951695/ultrasonic-distance-sensor-5v-hc-sr04 2019-10-07 https://elecena.pl/product/15951695/ultrasonic-distance-sensor-5v-hc-sr04 2019-12-09 https://elecena.pl/product/15951695/ultrasonic-distance-sensor-5v-hc-sr04 2019-12-14 https://elecena.pl/product/15951695/ultrasonic-distance-sensor-5v-hc-sr04 2022-02-21 https://elecena.pl/product/15951695/ultrasonic-distance-sensor-5v-hc-sr04 2025-04-12 https://elecena.pl/product/15951695/ultrasonic-distance-sensor-5v-hc-sr04 2025-04-14