-Description Pull back the sue. If you don't put a load on it, it won't go forward even if you pull it back.If you put a ball on it... Let's think about how many balls you need to put on it to make it run.It will start running!The appropriate weight is 15g.Try it out with different things on it. It would be fun to have this set of equipment as well. https://www.ebay.com/itm/266800436390 -Shipping