8Mark bolt(Small(Partial thread(Fine Steel Trivalent black(Black) 12X130(Partial thread(1.25 Pitch 1.75

These are S45C bolts with a strength class of 8.8T, marked with either "7" or "8" on the head.
They feature a regular hexagonal head and are tightened using a wrench or spanner.
They can be tightened more securely than slotted or cross recessed screws.
Full thread = A bolt where the entire length from the hex head to the tip is threaded.
Partial thread (medium bolt) = A bolt that is threaded from the tip partway up the shank.
Partial thread length calculation (approximate guide):
L = up to 129     Nominal thread diameter × 2 + 6
L = 130 to 219   Nominal thread diameter × 2 + 12
L = 220 and above   Nominal thread diameter × 2 + 25
Example: For an M10×250 partial thread bolt, since L (length) is 220 or greater, the thread length is 10×2+25 = 45mm.
Thread Pitch & Hex Width Across Flats List　Hex Bolt Encyclopedia

• 8 Mark bolt Small Partial thread Fine pitch
• Nominal thread diameter (d) M12
• Pitch (p) 1.25
• Length under head (ℓ) 130.0
• Head height (k) Nominal 8 Tolerance ±0.3
• Width across flats (s) Nominal 17 Tolerance 0,-0.8
• Width across corners (e) Approx. 19.6