An essential step for making a quality pen or other project is to square the end of your tubes before turning. WoodTurningz 8-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), and pilot bores in 7mm, 8mm, 10mm, 3/8", and 27/64". 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.
(Previously the BTRIMKIT9)