ISO 10642, steel 08.8, zinc-plated, blue passivated (A2K)
NoticeISO 10642 replaces DIN 7991 | There is some limited similarity (some head heights and head diameters have been changed | nominal Ø M18, M22, M24 are omitted | Stainless steels removed | strength classes 10.9 and 12.9 added).
These screws can only be subjected to limited loads due to their head geometry, see DIN EN ISO 898-1