111.1mm (4.375")

There are numerous pen refills that fall into this length category. This is the length of the standard (euro, international) ceramic safety rollerball (RB) refill. These rollerball refills can vary from 110mm to 112mm. Other refills of this length include the Cross Selectip, Parker 5th, Waterman ballpoint, Pilot G2, and numerous gel roller refills.