A few years ago, I received this as a gift from a foreign friend, and I displayed it a few times before putting it away. The items are in good condition, but the box is slightly damaged. Now, as I'm checking them one by one, it seems there are batteries inside that make music on the back. I haven't confirmed whether the sound works. Each one weighs 100g, and the sleds are made of plastic. When connected, they are about 50cm long.