Reply To: DIY Beolab 8000 Wood frets (STLs included). February 27, 2023 at 7:27 am #16733 matadorModerator Paris FranceTopics Started 37Total Posts 538 The 4mm clamps are designed for 4mm thick wood bits. The 5mm clamps are designed for 5mm thick wood bits easier to find in nothern countries it seems.