TWSBI - Diamond Mini Fountain Pen

Piston filler type fountain pen.

Comes in EF, F, M, B

Roughly the same height as an iPhone 5 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)

About 1 inch shorter than a Diamond 580 fountain pen. 

Please note: Ink is NOT included

A quick no brainer guide in choosing nib sizes in an overly complicated fountain pen world:

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
Stub nibs are italic in writing style (have a special card or invitation to write?)