This is a low profile imbus (hex-key) bolt used in the cross bar stabilizer, and in the hatch lock receiver (I think the upper too).
The nuts on the Upper A-arm are non standard. They are M12x1.5 and I used rust free DIN934.
The bolts that hold the caliper to the wheel hub are non standard. They are M12x1.5x80 in 10.9 strength what is called "hochfest feingewinde"