TWSBI Fountain pen nib, Parts series Steel (Diamond Mini

EF / F / M / B nibs

Spare Nib Sets for Diamond Mini and Diamond Mini AL fountain pens.
Easy change: simply unscrew and screw on a new one

TWSBI doesn't make spare nibs for the Classic fountain pens.
If you want to change the nib on your Classic fountain pen, you have to buy the Mini nib set.
However, the grip sections of the two fountain pens are different, so you will need to gently* pull the nib and feeder straight out of the grip section and swap them over.
*The nib and feeder are fragile
Go have a look at the PDF file in the 'Specifications' section below to see how to do this manipulation.