PIR motion sensor
Runs on 5V-16V power (if you need to run it off of 3V you can do that by bypassing the regulator, but that means doing a bit of soldering). Digital signal output is 3.3V high/low. Sensing range is about 7 meters (120 degree cone)
For a full tutorial with wiring diagrams, code examples and project ideas, PIR sensor tutorial page!
Screw hole distance: 28mm
Screw hole diameter: 2mm
Height (with lens): 24.66mm/0.97in