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 : Less than 2mA,effectualangle: Less than 15 ranging distance : 2cm~500 cm resolution : 0.3 cm There are 4 pins out of the module: VCC , Trig, , GND. So it's a very easy interface for controller to use it ranging. The all process is: pull the Trig pin to high level for more than 10us impulse, the module ranging; Finish ranging, If you find an object in front, pin be high level, and based on the different distance, it take the different duration of high level. So calculated the distance easily: Distance = ((Duration of high level) * ( :340m/s))/2 Color: As Shown Material: PCB Package Contents: 10 * Ultrasonic Module -SR04 Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.