Hex socket head cap screw(Nihon Byora(Coarse Steel Unplated 4 X 25 Pitch 0.7

This is a bolt with a cylindrical head featuring a hexagonal socket.
Tightening is performed using a hex key (Allen wrench). Although classified as a bolt, it is most commonly used without a nut.
It is also known as a cap screw or socket screw. Unlike open-end spanners or wrenches used to tighten hex bolts, which require clearance space around the fastener, a hex key requires no such surrounding space.
For this reason, the use of hex socket head cap screws enables work in confined spaces and contributes to the miniaturization of machinery.
Their appearance has also led to their increasing use for decorative and design purposes.

• Hex socket head cap screw Nihon Byora Coarse pitch
• Nominal diameter (d) M4
• Length under head (ℓ) 25.0
• Pitch (P) 0.7
• Thread length (b) Reference 20
• Head diameter (dk) Max 7.22 Min 6.78
• Neck diameter (da) Max 4.70
• Body diameter (ds) Max 4.00 Min 3.82
• Head height (k) Max 4.00 Min 3.82
• Under-head fillet (r) Min 0.2
• Hex socket width across flats (S) Nominal 3.0 Max 3.08 Min 3.02
• Hex socket depth (t) Min 2
• Head chamfer (v) Max 0.4