Features Used on machine tools for comparing gages Ideal for checking precision measuring tools Useful for measuring parallel surfaces These standards are the ones used for all micrometers furnished with standards Made of special tool steel in rod form with ends hardened and accurately lapped to a spherical radius Larger sizes available on special order Specifications Made in America: Yes Set Quantity: 12 Set Lengths (in): 12" to 23" in steps of 1" Diameter (in): 7/16" End Geometry: Spherical Handle Type: With Insulating Handle