This is a custom made fountain / rollerball pen. Ebonite is a hard vulcanized rubber material. Quite expensive compared to other materials.
It comes in 1 meter long rods i just order the ones i like. It is a long process just to make a rod.
Their ebonite is very high quality. They also make high end fountain pens with it. Ebonite just feels good in your hand it is hard to explain this. It takes threads very well.
Seems to be very durable. I dropped a pen cap on my concrete floor it bounced up 3 feet and i caught it. Pen cartridge holder and nib section are made from black ebonite.10mm threads for cartridge holder and nib section. The thread for the jowo nib is 7.4mm.
12 mm triple lead threads on cap and body. Total length of pen is 5 1/4 inches.
Cap length is 2 9/16 and cap diameter is. 570 or just over 9/16 inches. 510 or just over 1/2 inch. This pen uses a jowo #6 nib. This pen also uses a rollerball cartridge.The spring goes in end of pen body. It comes with a beaufort ink cartridge. Also a k5 ink converter and ink cartridge. The cap has a shallow recess to go over the pen body. This gives it a nice finished look. I wanted to make a pen to give both options.
A spring drops in the bottom of the pen body and puts pressure on the rollerball cartridge. The spring is used for the rollerball cartridge only. I have never seen this combination offered. This item is made of black ebonite and ebonite, rollerball pen, nikko ebonite, beige and black, mottled ebonite, yellow and black, red and black, orange and black.