In the above image I'm showing two Pentel Color Brush Pens. The one on the bottom is brand new, but the one on the top is an old one I've taken apart. The way Pentel sells these pens is that the bottom section can be replaced with another handle that is already filled with ink.…
Color Brush™ - Pigment Ink - Black – Pentel of America, Ltd.
Pentel : Pigment Brush Pen (Gpp3 / P3) Refill : 4 Cartridges Of Black Ink
Refilling a Pentel Pocket Brush Pen With Fountain Pen Ink (Iroshizuku) // The Pocket Traveler
GFL Pentel Stationery of Canada
Pentel Arts Black Pocket Brush Pen and Refills
Pentel Brush Pen Refill Black 4pc
Pentel Arts Water-Based Color Brush Pen Refills - Set of 2
Pentel refill ink for color brush pen gray 137
Pentel Colour Brush Pen Refill, Light Green #111
Pentel Fude Brush Pen Extra Fine (XFL2F) + Cartridge (XFR-AD) 2-Pack
Pentel Pigment Ink Brush Pen - Medium