WYPH Ultrasonic Module HC-SR04 Distance Measuring Ranging Sensor for Arduino Pack of 10pcs Using IO trigger for at least 10us high level signal The module automatically sends eight 40 kHz and detect whether there is a pulse signal back If the signal back, through high level ,time of high output IO duration is the time from sending ultrasonic to returning. Test distance = (high level time velocity of sound (340M/S) /2 Power supply :5V DC, quiescent current : &lt;2mA,effectualangle: &lt;15 ranging distance : 2cm~500 cm resolution : 0.3 cm Package Content: 10pcs HC-SR04