Review on 🛠️ Kutzall Extreme Ball Nose Burr: Versatile Woodworking Attachment for Dremel, Foredom, DeWalt, Milwaukee - Very Coarse, Tungsten Carbide, 1⁄8" Shaft, 1⁄4" Dia. X 1⁄2" Length, BNX-14-EC by Chris Sanders

I know it says "tool diameters are approximate and do not include coating thickness" but I didn't expect it to be around 2mm are more! Approximately there will be a tenth or two variations. Nice ridge but totally useless for me as the size is about 65% larger than advertised. This is a measurable difference that should have been reflected in more detail. To clarify, the rod diameter is perfect, but the tungsten coated drill head is about 5mm wide, not about 3.1mm as advertised. If you want a 5mm wide head I would say this is a good bit and will probably hold up well.