This performance of the ultrasonic sensor distance measuring module is stable measure the distance accurately. The module is with High precision blind spots (3cm) super close. This module provides a full set of ranging process. - Model: HC-SR04 - Color: Blue + Silver - Working voltage : 5V(DC) - Static current: Less than 2mA. - Output signal: Electric frequency signal high level 5V low level 0V. - Sensor angle: Not more than 15 degrees. - Detection distance: 2cm~450cm. - High precision: Up to 3mm - Mode of connection: VCC / trig(T) / echo(R) / GND - Module Working Principle: - Adopt IO trigger through supplying at least 10us sequence of high level signal - The module automatically send eight 40khz square wave and automatically detect whether receive the returning pulse signal - If there is signals returning through outputting high level and the time of high level continuing is the time of that from the ultrasonic transmitting to receiving Datasheet: http://m5.img.dxcdn.com/CDDriver/CD/sku.133696.pdf