Square head bolts
This Japanese Industrial Standard specifies the steel square head bolts for general use (hereafter, referred to as “bolts”).
Further, the strength class column II (4T) of mechanical properties specified in this Standard will be abolished on April 1, 1999.

Check out other specifications
Hexagon Screws – Thread Approximately to Head – Metric Thread Type g
ISO general purpose metric screw threads – Tolerances – Part 1: Principles and basic data
Hot rolled products of structural steels — Part 6: Technical delivery conditions for flat products of high yield strength structural steels in the quenched and tempered condition
Hexagon head bolts with metric fine pitch thread – Product grades A and B
FORGED EYE BOLTS
CHROMIUM/ZINC CORROSION PROTECTIVE COATINGS FOR FASTENERS