Diameter: 3.4mm

Suitable for deli fountain pens and some fountain pens made in China (see below list of brands and models found in Google search)

- Hongdian: Almost all models, including the Hongdian 1861 Black Forest, 1850, 1837, 517, 6013, and the M2 series

- Wing Sung: Various models that require the wider bore, often identified in 3.4mm cartridge listings

- Jinhao 80: Specifically noted to fit 3.4mm cartridges and not the smaller 2.6mm ones

- PenBBS: Select models