7markHex bolt(Small(Full thread(Coarse Steel Trivalent black(Black) 8 X 25 Pitch 1.25

S45C bolts with a strength class of 8.8T, marked with the number 7 or 8 on the head.
These bolts have 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 under the head is threaded. (Generally applicable for lengths of 30mm or less)
●Partial thread (medium bolt) = A bolt that is only threaded from the tip partway up the shank.
Partial thread length calculation method (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 more, the threaded portion = 10×2+25 = 45mm.
Thread Pitch & Hex Width Across Flats Reference Chart　Hex Bolt Encyclopedia

• 7 Mark Hex bolt Small Full thread Coarse
• Nominal diameter M8
• Length under head (ℓ) 25.0
• Width across flats x Head height (BxH) 12x5.5
• Pitch 1.25