Abula You can also use most parker-style refills, so you can turn it into a ballpoint instead of a rollerball.
Here is the list I lifted from www.wellappointeddesk.com:
Diplomat EasyFLOW Ballpoint Pen Refill
Faber-Castell Ballpoint Pen Refill
Faber-Castell Scribero Gel Ink Roller Refill
Fisher Space Pen Refill, PR Series- Colors (Bold, Medium, Fine)
Fisher Space Pen – Universal Ballpoint Refill
Foray (Office Depot) Ballpoint Refill for Parker (Medium)
Here is the list I lifted from www.wellappointeddesk.com: