MRC:
The specification,standard,or manufacturers reference,and the classification designation,such as class,condition,temper,and the like,that identifies the screw material.CYAW
Screw Material Specification:
Qq-s-630 federal specification 1st material response or qq-s-631 federal specification 2nd material response or qq-s-634 federal specification 2nd material response or qq-s-409, grade 2 federal specification 2nd material response or qq-w-409, grade 3 federal specification 2nd material response or qq-w-409, grade 4 federal specification 2nd material response