Durable - The head is made of hardened steel, ground, and nicely polished - 2-5/8" (66mm) long and 1/8" (3mm) wide. Head is graduated both left and right to 30, 45, and 60 degrees. Easy To Use - A tempered rule that's accurately machined divided, is smoothly fitted to the head and can be locked in position by a knurled nut. The center of the head is recessed so that the tool will lay flat to permit more accurate measurements. Convenient - This depth gage has an added feature permitting its use as a protractor for measuring angles. It is a simple, handy tool that is a welcome addition to any machinists toolbox. Accuracy You Can Count On - Starrett precision measuring tools exceed accuracy and performance requirements of national and international standards, providing excellent fine precision tools for industrial, professional and consumer markets worldwide. The Standard for Excellence - Manufacturing quality tools that provide consistent and reliable performance since 1880, Starrett's commitment to product excellence, has earned them a reputation as one of the most trusted names in the industry.