Hexagon socket head cap screws of wit standard (1/4 W and 5/16 W) are required for repair of imported equipment. Hexagon socket head bolts of the wit standard are not very circulated and are very helpful. Unfortunately, the diameter of the cap part is the same diameter as the JIS standard bolt of 6 mm and 8 mm respectively. Therefore, 5/16 W can not be used for counterbored hole of 0.48 inch actually measured. Because it was awesome, I wanted to match the cap part to overseas standards.