Hex socket head cap screw P=3(Coarse Stainless steel Unplated 5 X 20 Pitch 0.8

This is a bolt with a hexagonal socket in a cylindrical head. Tightening is performed using a hex key (Allen wrench).
In most cases, it is used without a nut. It is also known as a cap screw or socket screw.
When fastening a hex bolt, a wrench requires working space, whereas a hex key does not.

Cap Bolt　
Hex Socket Head Cap Screw Encyclopedia
Cap Bolt　P=3

• Hex socket head cap screw P=3 Coarse pitch
• P=3 (With spring washer + JIS flat washer)
• Nominal thread diameter M5
• Length under head (L) 20.0
• Coarse pitch 0.8
• Head diameter (dk) Nominal 8.5 Max 8.72 Min 8.28
• Head height (k) Nominal 5 Min 4.82
• Hex socket width across flats (s) Nominal 4 Max 4.095 Min 4.02
• Hex socket depth (t) Min 2.5
• Flat washer (D x t) 12 x 0.8
• Spring washer (d) Max 8.5
• Spring washer (b x t) 1.7 x 1.3
• Incomplete thread section Max 4.8
• Partial thread range L55 and above
• Partial thread Thread length 40-44
• *Full thread Thread length = L dimension - Incomplete thread length