There are many tools for finishing concrete surfaces, but this article will deal only with those tools that are used to finish horizontal concrete surfaces. A straightedge or strike-off rod is usually a straight piece of 2 by 4 or a 1 by 4 with a one and a half by 2 inch shoe strip attached to the bottom. It can, however, be made of any straight piece of wood or metal that has sufficient rigidity. The straightedge should be longer than the widest distance between the screeds or edge forms. It is the first finishing tool used by the cement mason after the concrete is placed and is used to strike off or screed the concrete surface to proper grade. After the concrete has been struck off, hand tampers can be used to compact the concrete into a dense mass. They are used on flatwork construction with low-slump concrete because such concrete is usually quite stiff. Tampers are used to force the large particles of coarse aggregate slightly below the surface in order to enable the cement mason to put the desired finish on the concrete surface. The tamper should be used only sparingly and in most cases it is not recommended and not necessary. A darby is a long, flat, rectangular piece of wood, aluminum or magnesium from 30 to 80 inches long and from 3 to 4 inches wide with a handle on top. It is used to float the surface of the concrete slab immediately after it has been screeded, to prepare it for the next step in finishing. This tool should be used to eliminate any high low spots left by the straightedge and to sufficiently embed the coarse aggregate for subsequent floating and troweling. A bull float is a large, flat, rectangular piece of wood, aluminum or magnesium, usually 8 inches wide and 42 to 60 inches long with a handle 4 to 16 feet in length. The function of the bull float is essentially the same as that of the darby. Edgers come in many sizes; all are about 6 inches long and vary in widths from 1 and one half inches to 4 inches with lips from one-eighth to five-sixteenths, having radii from one-eighth inch to one and a half inch. Edgers are used to produce a radius at the edge of the slab. This improves the appearance and reduces the risk of damage to the edge. Jointers are about 6 inches long and vary from 2 to 4 and one-half inches wide and have shallow, medium or deep bits running from three-sixteenths an inch to three-fourths an inch in depth. A jointer is used to cut a joint partly through fresh concrete. These joints are used to predetermine the location of any possible cracks.