These corrugated steel bars are used as tension devices in the construction of concrete slabs and walls, as well as decorative/ornamental grille work. When used in concrete constructions, these help to strengthen and hold concrete when it is compressed, and come in a wide variety of sizes to fit various building construction needs. At ARC. AVAILABLE IN 3/8â?? (10mm), 5/8 (16mm), (20mm), (12mm), 1 (25mm) and 1 (32mm)