Socket head cap screws M1.6–M20: DIN 912, ISO 7380 and DIN 7991, in A2-70, A4-70 and 12.9 steel. Socket head screws drive from the inside, so the head can be a cylinder rather than a hexagon — smaller for the same strength, and able to sit in a counterbore so the top surface stays flat. The three socket-drive families are often confused: DIN 912 / ISO 4762 cylindrical head cap screws, ISO 7380 button head screws, and DIN 7991 / ISO 10642 countersunk screws. In China the same parts are made to GB/T 70.1, GB/T 70.2 and GB/T 70.3.
Metric coarse thread is standard from M1.6 to M20. Stock materials are 304 (A2-70) and 316 (A4-70) stainless steel, 12.9 and 10.9 alloy steel, plus nylon (PA66) and TC4 titanium for light-duty and non-magnetic applications. Length is measured under the head on DIN 912 but overall on DIN 7991 — check that before you specify a replacement.
For a general-purpose part, start with the DIN 912 socket head cap screws. For dimensions, thread length rules, counterbore data and grade selection, read the DIN 912 sizing and grade guide. Single pieces are orderable — there is no minimum order quantity, and freight is quoted separately so you see the real landed cost.
