Since they will not be used outdoors, I'm not going to send them home and the problem is over / cosmetic and not affect the application.
With regard to function, they allow mobility on a smooth surface and two people guiding the sleds that the four wheels are rotating, large wheels allow for better mobility.
What to wear, you must put one in each of the ski under my belt, which requires the lifting of the tray and push the cart under heavy sled complicate the calculation behind the cart under his belt, so be careful.
This is useful products, and do what must be done within the guidelines above, as the quality they are made in China.