Round section steel bars with ribbed surfaces, or ridges, to facilitate their adherence to concrete when used in the construction industry. They are manufactured in strict compliance with the specifications that indicate the yield point, tensile strength and its elongation. The specifications also indicate the dimensions and tolerances. They are known as construction bars, corrugated bars, construction irons or corrugated iron. Construction bars are identified by their diameter, which can be in inches or millimeters. The usual lengths are 6, 9 and 12 meters long.