5PCS HC-SR501 PIR Infrared IR Sensor Body Motion Module DC 4.5-20V + 5PCS 5V Electromagnetic Active Buzzer for Arduino Raspberry Pi

4 of the IR motion sensor modules were fine, but 1 was seemingly broken with a short circuit somewhere. When I connected it to my Arduino, nothing powered on, and the Arduino chip itself became hot at the power input. Maybe I just got unlucky. As I said, the other 4 were fine, and luckily, I only needed 4 for what I was doing. The fifth was intended to be a spare (and I guess I needed it).No complaints with the buzzers.

Works great as a motion sensor. Nice and small. Easy to use. You'll have to add a delay in software when using this with your project if you want to keep whatever on for longer time. They come individually bagged, in one larger bag. No complaints.

These are great little compact motion sensors. They aren't quite as sensitive as their larger counterparts, especially at a distance, but that's the tradeoff for their compact design.

The soldering is a bit sloppy and on some the sensor is a bit crooked. But they work, and for the price they are great.