If you have an Arduino or Raspberry Pi, it's a "plug and play" dream using the four standard pins: VCC, Trig, Echo, and GND . The Catch: HC-SR04 Ultrasonic Sensor Module - Quartz Components

For such a cheap component, it’s surprisingly accurate, often within 3mm .

Most "packs" come in sets of 5 or 10. This is lucky because, in the world of breadboarding, things occasionally "stop working" after one too many wiring experiments. Performance Highlights: