Opus 88 Koloro Blue fountain pen
The Opus 88 Koloro Demonstrator is a sturdy fountain pen made of acrylic (closed length 147.5 mm). The pen has a steel nib available in different line widths.
The pen must be filled with the supplied pipette (so-called eyedropper), as is common in some Japanese fountain pens. Connected to the rear cap, there is a rod in the holder with a gasket inside at the other end to separate the ink guide and reservoir. Slightly loosening the rear knob allows the ink guide to be supplied with ink. Tightened again, the two compartments are separated and the large ink supply (approx. 3 ml) is safely stored.
Opus has been producing vital parts for various other stationery manufacturers since 1988 as an OEM supplier. In 2017 it was decided to release pens under their own label under the brand name "Opus 88".