Many children like to make roads, airfields, and layouts out of blocks and drive matchbook sized cars, planes, and trains on them. Curves and intersections are needed in order to make more complicated lay-outs. These can be made in two thicknesses: block thickness (1-3/8") or plank thickness (11/16"). Many of the simple sets of blocks lack road planks. For them, we have here block thickness intersections and curves. The same shapes are also available in road thickness which is half the thickness of Blocks. If your blocks came from us, you probably have road planks and might prefer to have thinner roads. But if all of your blocks are 1-3/8 thick, these intersections would be correct for you.