The "poor man's" accelerometer! Tilt sensors are switches that can detect basic motion/orientation. The metal tube has a little metal ball that rolls around in it, when its tilted upright, the ball rolls onto the contacts sticking out of end and shorts them together.
Product Dimensions: 23.0mm x 5.0mm x 5.0mm / 0.9" x 0.2" x 0.2"
Product Weight: 1.0g / 0.0oz