This is a low sensitivity, directional vibration-induced trigger switch. Inside is a very soft spring coiled around a long metal pin. When the switch is bumped from the side only, the spring attached to the first pin touches the center pole to make contact with the second pin. So when there's a bump, the two pins will act like a closed switch. When everything is still, the switch is open. Great for educational projects and wearables!
Compared to most vibration switches, this one is flat, and will solder nicely into a PCB without sticking up, and is also breadboard friendly.