M16 - Outer:30.0mm Inner:17.0mm Thickness:3.0mm. M8 - Outer:16.0mm Inner:8.4mm Thickness:1.6mm. M12 - Outer:24.0mm Inner:13.0mm Thickness:2.5mm. M10 - Outer: 20.0mm Inner:10.5mm Thickness:2.0mm. M4 - Outer: 9mm Inner:4.3mm Thickness:1.0mm.
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