(-)Flat head machine screw(Coarse Brass Unplated 8 X 25 Pitch 1.25

The head of a round machine screw is nearly hemispherical in shape, similar to today's truss head machine screw. The flat head machine screw has a low-profile cylindrical head. It was commonly manufactured in the past due to its simple production method.
Machine Screw Head Dimensions List　Encyclopedia of Round & Flat Head Machine Screws

• Slotted (-) flat head machine screw, Coarse pitch
• Nominal diameter (d): M8
• Length under head (ℓ): 25.0
• Pitch (P): 1.25
• Head diameter (dk): Nominal 14.0, Tolerance 0,-0.8
• Head height (k): Nominal 5.2, Tolerance ±0.2
• Slot width (n): Reference 1.6
• Slot depth (t): Reference 2.8