TWSBI Diamond Mini Fountain Pen

Piston filler type fountain pen.

Comes in EF, F, M, B, stub1.1, stub1.5 nib sizes

Roughly the same height as an iPhone when capped and stored away.

Slightly longer when cap is posted on the pen (perfect length for writing when cap is  posted on the back)

Roughly 1 inch shorter than a Diamond 580 fountain pen.