Antler is a wonderful turning material, but figuring out how to hold the irregularly shaped blank in place for drilling and cutting to length can be difficult. That's why we're offering these blanks in pre-drilled form so you can minimize the risk of blowout or a lopsided blank. The ends have been squared off, but the tubes will need to be glued in place and the ends trimmed flush with the brass tubes in your chosen pen kit. They are drilled for a 3/8'' tube, and will fit many of our Bolt-Action Pen Hardware Kits (#55946, sold separately).