The S234C Standards Set is designed for checking and setting Starrett S436.1 and S436 Micrometer sets with 0-3" range. These End Measuring Rods or "Standards" are also used on machine tools for comparing gages, checking precision measuring tools, for measuring parallel surfaces, and many other types of work. They are made of special tool steel in rod form with ends hardened and accurately lapped to a spherical radius. Rods or Standards are for checking and setting micrometers of 2" to 3" capacity. These standards are the ones used for all micrometers furnished with standards. Larger sizes available on special order. Starrett tools are designed to be user-friendly. Whether youre 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.