9/16x2 1/4 UNF BOLT ZP GR 5
1/2" diameter & larger Grade 5 bolts are becoming obsolete, in future these will only be available in Grade 8.
Thread = 18 TPI (Thread per Inch)
UNF (Unified National Fine Thread)
Hexagon head Across the Flats ( AF ) = 13/16"
Medium High Tensile Grade 5
Zincplated Finish