Gel ink refills from Ohto that can fit all the Ohto Liberty pens such as the Ohto Fine, Orca and more. These refills are the same size as the C-30X (i.e. C-305, C-307, C-310 etc) Ceramic Roller Ball series and are interchangeable. The G-30X series has gel based ink instead of the water based ink of the C-30X line. 0.5 mm, 0.7 mm and 1.0 mm sizes available.
This is currently my absolute favorite ink replacement cartridge. It's silky
smooth and doesn't ever skip. The Pentel KLR7 and LR7-A cartridges are solid as
is the Pilot BLS-G2 and Zebra JF 0.7. I've even gone to some of the higher-end
Waterman, Lamy (M66, M63), and Mont Blanc rollerball cartridges and none are as
good as this cartridge. I've tried well over 100 different ink cartridges over
the past year and THIS is the one that I use every single day. Highest possible