An essential step for making a quality pen or other project is to square the end of your tubes before turning. WoodTurningz 9-piece barrel trimming kit has everything you want in a trimmer kit. You get both 5/8" and 3/4" HSS cutters (allowing you to set up two sizes at once), pilot bores in 7mm, 8mm, 10mm, 3/8", and 27/64" as well as the sleeve you will need for 8mm pencils. This is the only kit you need that includes the pilot bore for the Mesa, Sierra, and Gatsby pens, as well as any of your other 27/64" kits.