Your search for "acme rollerball" revealed the following:
Rollerball Pen Refills Glossary
Although the tips may look the same, a Rollerball Pen refill is quite different than a Ballpoint Pen refill. For...
Refill Size Guide
Kindly note that refill pictures are for reference only and are not shown to scale. The main characteristics you are...
Ballpoint Pen Refills Glossary
The most common type of pen in the world today is a ballpoint pen. Easy-to-use with either a twist-action mechanism...