Tombow rollerball refills are known for their point sizes. They come in Extra Fine, Fine and Medium. Rare for a rollerball. However, since they are literally liquid ink they don't last as long as say a standard ink ballpoint refill. All Tombow owners would gladly trade the fluid writing feel for a few more pennies.
Give the Tombow liquid ink writing system a try. Many never go back to regular refills. Here is a link to the current Tombow pens we carry. Tombow pens