The Fowler 52-480-050-0 Steel Straight Edge with 18" length is made of selected steel and is hardened for superior wear resistance. The straight edge is matched to precision masters to ensure precision. It has width and thickness that are carefully determined to provide optimum rigidity-to-weight ratios. Fowler, an American company, manufactures premium inspection and measurement instruments like electronic indicators, calipers, bore gages, and micrometers. The company, founded in 1946, is headquartered in Canton, MA.