Each pen is individually handcrafted and begins as a single lead-free brass rod. I meticulously craft them into the final shape on a manual lathe. I've designed them to be as simple as possible - there are only 6 parts in each pen. Each pen will ship with one of my favorite fine tip gel cartridges installed - the Pentel Energel 0.4mm needle point or the Pilot G2 0.7mm. Two styles of ink refill are available: - Pilot G2 - features a slightly larger opening to accommodate the Pilot G2 tip - Pentel Energel - features a smaller opening that is also compatible with many other refills (Sakura Ballsign Knock, Zebra Sarasa Dry and others) The mechanism is simple and secure: carry confidently in your pocket or purse and never worry about an accidental ink stain. If you'd like a different color of ink than black, or a different type of cartridge when it ships, let me know and I'd love to accommodate any reasonable requests! Dimensions 8mm x 142.5mm (5/16” x 5.6”) 31.75 g (1.12 oz) Please note: The finish on this pen is raw brushed brass. This allows a nice patina to develop that is truly unique to you.