A majority of the time this pen will have a body and separate cap. Just like a fountain pen. This is primarily driven by the need of the liquid ink refill to be capped (sealed). Without capping the refill will begin to dry.

There are roller ball technology (meaning liquid ink) refills which do not need to be capped to perform. These are referred to as, "capless" roller balls. You will find roller ball pens available with this type of refill in twist-action bodies. These are sometimes referred to as Ballpoint convertibles (convertible to roller ball technology with the use of a capless roller ball refill).

There is now a technology which blends fountain pen writing and roller ball technology. In 2006, Monteverde introduced to the U.S. market the MEGA InkBall which is a roller ball tip that has a wick ink feeding system. Consequently, the pen uses and writes as a fountain pen but has no traditional nib.