The Fowler 52-750-006-0 Cylindrical Square is used for checking squares, height gages, and other instruments. This precision measuring tool is hardened and the ends are lapped to 90° angular accuracy, and an accuracy of ±.0001". It is 6 inches in height and has a 3-inch diameter. Includes a cylinder square with handle and a case. It comes with a 1-year warranty. 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.