The Starrett No. 600 6in Metal Hook rule 4R grad measuring tool is a precision metalworking inspection and measurement tool. With a 6-inch length and 4R graduation style, this hook rule is designed for accuracy in measuring tasks. Made of durable metal, this tool is ideal for professionals in the CNC, metalworking, and manufacturing industries who require reliable and precise measurement tools. The inclusion of a rule No. 418 enhances the versatility and functionality of this high-quality measuring tool.