Iris Diamond 580 Fountain Pen, TWSBI

This pen features a clear demonstrator body with rainbow-colored iridescent trim and a stainless steel nib accented with iridescent color.

The idea behind the TWSBI Diamond 530, 540, and 580 was to go back to basics and capture the simplicity and elegance of traditional writing instruments. It was their goal to bring the past back to life by creating a traditional fountain pen that even modern-day society can appreciate.

TWSBI Diamond 580, a classic fountain pen with a piston ink-filling system. By fusing the traditional mechanisms of the fountain pen with a modern industrial design, they have created an eye-catching fountain pen that is simultaneously appreciative of the past and relevant in the present. The Diamond 580 comes with a benchmark ink-filling mechanism and has all detachable parts. They felt that it was important to allow the user to disassemble and reassemble the pen and completely experience the traditional aspects of owning and using a fountain pen.

If you write small, go with an EF.
For the normal writer, F is the most popular
If you tend to lean on a bigger font, M will be perfect.
B is for statements! Sign a check in B, write a header in B, do some coloring/shading in B.

580 has increased ink capacity, about 30% more than 530
580 has improved the smoothness of cap thread turning
Please note: ink is not included