This frame is pre-punched with 21/64 inch holes which are intended for 5/16 inch hardware. Equivalent metric hardware is listed below:

1 Bolt: 5/16 inch x 2.5 inch ~ M8x60<br> 2 Bolt: 5/16 inch x 4 inch ~ M8x100<br> 3 Bolt: 5/16 inch x 5.5 inch ~ M8x140<br>