Barrel diameter: 14.8 mm - 13.25 mm. Cap diameter: 16 mm - 14.25 mm. Section grip: 11.5 mm.Section pinch: 10.5 mm. Schmidt k5 converter or comparable. Little pen designs offer quality, handcrafted fountain pens. Every pen is created by me personally in my shop in north carolina. I use only hand tools and a wood lathe, no automation or mass manufacturing. This process ensures that every pen i create is a unique work of art. The majority of my fountain pens are made from alumilite resin blanks, some of which have been custom made in my shop. I use calipers to accurately measure each piece and then turn down the body, cap and section on a lathe. Final sanding, polishing and buffing create a truly spectacular finish. This intensive manual process ensures a quality writing instrument to be enjoyed by the user for years to come. I hope you will enjoy my fountain pens as much as i enjoy making them. The pen in the photo is the pen you will receive. Pens offered by little pen designs are handcrafted in the united states (north carolina). This item is made of polyester resin and alumilite.