i lik these guys:
https://www.amazon.com/Pilot-Retractable-Premium-Roller-31277/dp/B0017TMMLS
super fine, just like coombz's mom
I have some very nice ones. Even have a couple that can survive air travel without spurting. But, these days I typically carry a Retro51 roller. They are a great company based in TX.
Here is their roller and fountain pen honoring the P51 mustang