The Starrett Combination Steel Rule Depth can be used to quickly obtain measurements in 64th of an inch or 1/2mm by simply adjusting the rule to the required depth. 0-150mm Range, mm/1/2mm. The gage consists of a nicely finished, hardened steel head and an accurate, machine divided, tempered steel rule. These rules are either our 610N (6 inch) or our 635N (150mm) models. Gage can be smoothly adjusted to the required measurement and then locked into position by a knurled nut. Base is cut out on one side, adjacent to the rule, permitting easier readings and more accurate measurement. 6" hook rule (236HC, ) also available, permitting readings from the edge of a workpiece to the edges of slots and shoulders. Graduated in 32nds, 64ths. Incorporating convenience and excellence, Starrett tools are designed to be user-friendly. Whether you're an experienced professional or an amateur when it comes to home improvement, our tools are handy and accessible. Starrett has set the standard for precision, quality, and innovation, our products are long-lasting and robust with excellent service and performance. Manufacturing long-lasting and easy to use tools that provide consistent and reliable performance since 1880, Starrett tools are made with the highest standard of quality and workmanship, manufacturing more than 5,000 various tools, gages, and instruments, providing fine precision tools for industrial, professional, and consumer markets worldwide.