Metric Coarse - Class 12.9 - Socket Head - Cap Screw Grade 12.9 high tensile or also known as allen screws. Manufactured to ISO Standard 4762 or DIN 912 in high tensile alloy steel. Our button head socket screws are available in black finish or a zinc plated finish for corrosion protection. Suitable for high strength bolting into threaded components and assemblies in manufacturing, mining and engineering industries. Supacheap bolts stock M3, M4, M5, M6, M8, M10 and M12 diameters and lengths to 50mm in certain sizes. Socket head cap screw lengths are measured from under the head.