Starwalker pen refill to convert from ballpoint to rollerball?

[fp525]

Hi all,
I have a Montblanc Starwalker ballpoint pen and from preliminary online research it seems like the rollerball refills are a different size than the ballpoint refill as the ballpoint twists and the rollerball has a genuine cap that is removed. Does anyone know if there's a rollerball refill that that fits into the Starwalker so I can use it as a rollerball rather than a ballpoint? Thanks!

[Chrissy]

It won't work because the BP is a twist action pen and the RB is a removable cap pen. If you put a RB refill in there it would quickly dry out. There have been gel type refills that used to fit Parker BP type pens but generally speaking RB refills need to go into a pen that has a removable cap.