Pilot Hi-Tec-C Coleto 2
This version of the Pilot Hi-Tec-C Coleto accommodates two refills. An iconic multi-pen that comes empty. The refills need to be purchased separately. I have gold and purple ink in mine. The plunger in the back swaps out with the refill to color match the ink.
Variants: There is a huge range of Coleto pens. Various colors, and number of refills they fit.
Refill: Mechanical pencil, eraser, and gel ink refills in proprietary size.