1. Nib Housing Compatibility The first factor is whether your pen’s nib housing is compatible with JOWO nib units. Not all fountain pens are designed to accept JOWO nibs, so it’s essential to confirm this before making any purchases. To help you get started, here’s a short list of well-known pen brands and independent makers that typically use JOWO nibs: Just Turnings Pens by Casey Esterbrook Franklin Christoph Leonardo Officina Italiana OPUS 88 Edison Mr Cypress Wancher Grav