Shanghai Jinrui Norm Parts Supplies Co.,Ltd is one of the leading wholesale quality carbon stee grade4/8/10 socket cap screw manufacturers and suppliers in China, welcome to buy wholesale quality carbon stee grade4/8/10 socket cap screw from our factory and company.
Hardware: a screw with a hexagonal recess in the head that is designed to be used with an Allen wrench <At the bottom of this hole is the Allen screw holding the two halves of the elevation knob together. — Patrick Sweeney, Gunsmithing: Rifles, 1999>
Usually the standard is regarded as DIN912
