5/8" x 18, National Fine Thread, 1-7/16" Hexagon Fractional Die, Carbon Steel, Ideal For Routine Maintenance, Repair Work & For Rethreading Where High Accuracy & Tolerance Thread Is Not Critical, Recommended For Use With Hexagon Die Stock, Die Can Be Used With A Wrench Or Socket When Space Is Limited , Designed For Hand Threading Work In A Variety Of Materials, Bulk Boxed.