A really versatile Ohto Refill for the old Ohto Horizon Pen (not the current GS01 model which takes the PS-107NP refill instead), Ohto Promecha and Pencil Ball Pen in tiptop use with this Black 0.3mm Refill - The Finest Line (Also available in 0.5mm and 0.7mm)
The Numbers:
893NP