The TWSBI Eco (short for "economic") is the cheapest fountain pen that uses the piston filling system. The resin TWSBI Eco fountain pen has a transparent barrel which makes the mechanism to fill it up with ink clearly visible. It gives the fountain pen a special character depending on the ink colour with which it is filled. The faceted cap of the TWSBI Eco gives the pen a powerful look. Choose your colour and nib size by selecting the desired combination of color and nib size (in brackets behind the color).
Specifications
Pen has a polished stainless steel nib with the logo engraved on it 
Included: Instructions and tools to disassemble the pen (only for the experienced user)

For the normal writer, Fine is the most popular
If you tend to lean to a bigger font, Medium will be perfect
Broad is for statements!! Sign a check in B, write a header in B, do some coloring/shading in B