Adaptors fit into the front of our pens and adapt them for a specific type of nib. For example, the Gillott 303 adaptor fits into the standard Pump Pen and Fountain Pen and lets you use a Gillott 303 nib and feed. 

The "standard Pump Pen and Fountain Pen" is designed for the largest nib - the Zebra Manga G nib. This is our most popular nib.