This is the HC-SR04 ultrasonic distance sensor now in Red! This economical sensor offers non-contact measurement functionality ranging from 2cm to 400cm with a ranging accuracy of 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.Note: This is the same ultrasonic sensor used with the XRP & XRP DIY kits.