10.9 Hex bolt(Nihon Byora(Coarse Steel Unplated 20X95X46 Pitch 2.5

Depending on the diameter size, partial thread applies to the following lengths and above:
6 X 25　and above
8 X 30　and above
10 X 35　and above
12 X 40　and above
14 X 45　and above
16 X 50　and above
20 X 55　and above
22 X 60　and above
24 X 70　and above
30 X 80　and above

Generally, a bolt refers to a screw used together with a nut. Among these, the hex bolt is the most common type, featuring a regular hexagonal head and tightened using a wrench or spanner.
It can be tightened more securely than slotted or cross recessed screws.
●Full thread = A bolt that is threaded all the way from below the head. (Generally applicable to lengths of 30mm or less.)
●Partial thread (partially threaded bolt) = A bolt that is threaded only from the tip partway up the shank.
Partial thread length calculation method (approximate guideline):
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 above, the thread length is 10×2+25=45mm.
Thread Pitch and Hex Width Across Flats List　Hex Bolt Encyclopedia

• 10.9 Hex bolt Nihon Byora Coarse pitch
• Nominal diameter (d) M20
• Length under head (ℓ) 95.0 Thread length 46.0
• Coarse pitch 2.5
• Head circular section diameter (dk) Nominal 20 Tolerance 0,-0.35
• Head height (k) Nominal 13 Tolerance +/- 0.35
• Width across flats (s) Nominal 30 Tolerance 0,-0.8
• Width across corners (e) Approx. 34.6
• End chamfer (Z) Approx. 2.5
• (b) is dx2+6 length 130 and above dx2+12 length 220 and above dx2+25