Retractable Twist Pen... Your signature is "mark". Make your mark loud and proud with a Genuine .308 Caliber Brass Shell Casing once fired by and procured from the US Military! Pen ink can be replaced with CROSS style 8514-2 ballpoint pen refill. Replacement instructions included. Although our products do not contain any active gunpowder or primers making them 100% safe for use, they resemble live ammunition; therefore, we do not recommend bringing them to locations where live ammunition is not permitted. Not recommended for use by children 12 years and younger. Because our Shell Casings and Projectiles are made from a once-fired US Military round, they may contain minor blemishes or scratches that are consistent with their history.