Bought this marble run thinking it would interconnect like the quadrilla set. But the design of this set is poor. As soon as my children place a marble in, the slightest force topples the whole thing and we have to rebuild it. The interlocking plastic squares are not robust enough to hold it up strongly and the blocks shift too easily as they are “placed” and nit locked in place. Like stacking normal wooden blocks really. Wish I'd spent the extra hundred and bought the quadrilla.