The Rotur 10mm Pen Accessory Kit includes 9.8, 9.9, 10mm tin coated drill bits and bushing kit for making the Premium Classic Rollerball and Fountain pen kits.  In softer timbers the hole drilled can end up being too big for the brass tube. By starting with the 9.8mm drill, you don't risk wasting blanks and ensure a good fit with the brass tube. SKU: AK10