The adaptation of the roller to the striking off of very wide concrete slabs has been a significant development. Slabs of excellent smoothness and flatness have been obtained in this way. An important consideration is that the cost of a small roller is low enough that almost any flat work contractor can afford to own one. The details of roller construction are relatively simple and no special tools or materials are needed. Probably the most important decision to make is what size of pipe to use for the roller. The pipe should be at least two feet longer than the width of the slab. This allows for some see sawing and helps keep the roller from running off the foundation plates and forms. To use the roller, position the roller on the foundation at the end of the slab. By placing concrete from each side, first with long chutes and then with short ones, you can place a uniformly wide area of concrete clear across the slab. The roller is moved back and forth, advancing into the unstruck concrete, until eventually it has covered all he concrete just placed. Then, before the roller is advanced to a new area, it should be lifted back over the small ridge left at the beginning of the area just rolled