Fowler's 53-666-000-0 Angle Blocks are made of solid hardened steel with specific angles. Includes 0.25- and 0.5-degree sizes to handle most angle requirements. Each 12 precision angle block set includes 1 thru 5 blocks in 1 increment and 5 through 30 blocks in 5 increments with an accuracy of 2.5 arc minutes. Simplify the setting and checking of angles during tooling, production, or inspection. This fast, accurate method eliminates time-consuming calculations, sine bars, and any setup errors. All blocks are precision ground and are 3" long and 0.25" thick. This product has a 1-year warranty offered by Fowler High Precision. 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.