Apex Tool Group LLC based in Sparks MD is one of the largest worldwide producers of industrial hand and power tools tool storage drill chucks chain and electronic soldering products, Used on concave, cinvex and flat surfaces, Rounded on 1 side, flat on opposite , Backs of all half-round bastard files are double-cut , Backs of all 4 and 6"" files are single-cut , Backs of all half-round second-cut files are longer than 6"" are double-cut SKU: ORSNO1817