Kaweco G2 ballpoint and G2 rollerball refills can be swapped to convert a SPORT pen from a rollerball into a ballpoint. Also for the SPECIAL series ballpoint.
Length 97mm.
Line Width: Fine (0.8mm), Medium (1.0mm), Extra Broad (1.4mm) and come in packs of 3.
Kaweco G2 ballpoint refills are the same size as the classic Parker style ballpoint refill, so they will fit all pens that use that refill.