This is a simple to use passive infrared (PIR) motion sensor with 4-position 2mm header (JST B4B-PH-K-S). Connect it to your Arduino with a 20cm 4-pin cable (5 pack, sold separately) and upload your code and when something moves in its detecting range, the sensor outputs HIGH on the SIG pin.
The detecting range and response speed can be adjusted by two potentiometers soldered on the circuit board. The response time is from 0.3s - 25s, and max 6 meters of detecting range.
