This fully adjustable rubber band powered ping pong cannon is sure to provide hours of entertainment. My classmates and I would launch ping pong balls from the third story balcony into a trashcan several yards below. It's surprisingly accurate and a whole lot of fun. The given tolerance works out well and provides a smooth axes of rotation. The only things you really need yourself are rubber bands, ping-pong balls, and something to latch onto the rubber band. I just bend a small piece of weld bar. It seems to work rather nicely. Right now I've retired my cannon and am currently using it as a stylish pen holder at work.