T8 screw M8 screw head size 18mm long, 14mm wide, 5mm thick. T10 screw M10 head size 23mm long, 17.6mm wide, 6.5mm thick. The opposite side of the M8 nut is about 14mm. Use a No. 14 wrench. If the nut is matched, it can prove that the screw is M8.
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