kuman 5pcs Hc-sr04 Ultrasonic Distance Measuring Sensor Module kit for Arduino UNO Mega R3 Mega2560 Duemilanove Nano Raspberry Pi 3 Robot K18 Update new version: Add 3 items as gift: 1*HC-SR04 Bracket + Male to Femal jump wires 20pin +10*cable ties for fixing HC-SR04 Ranging distance: 2cm~450cm.High precision: up to 0.3cm.Effectual angle:15 degree.Module precision:blind spots (2cm)-SUPER CLOSE Power supply :5V DC. Quiescent current : &lt;2mA.Size : 4.5 x 2.5 x 1.5 cm / 1.8x 1 x 0.59inch (L*W*T) Automatically send eight "40 kHz "and detect whether there is a pulse signal back. Mode of connection:4 pins VCC, Trig (control side), echo (receiver), out (empty),GND