Use these 6 blue/black fountain pen ink cartridges in a Pilot Parallel fountain pen. You can achieve gradated color variation with these mixable inks.
Pilot Parallel Mixable Colour Blue-Black - Ink Cartridges
PILOT Parallel Calligraphy Pen Set, 3.8mm Nib with Black and Red Ink C – toolsofwriters
PILOT 77307 PARALLEL Pen Ink Refills for Calligraphy Pens Red 6 Cartridges per $5.95 - PicClick
PILOT Parallel Mixable Color Ink Refills for Calligraphy Pens
Pilot Parallel Calligraphy Pen: Pilot's breakthrough nib design features 2 parallel plates & allows for sharp, monoline writing with the narrow edge,
Pilot Parallel Mixable Color Ink Refills for Calligraphy Pens, Black Ink, 6-Pack (77305)
Pilot® Mixable Color Pen Ink Refill
Pilot Parallel Pen Refills
PILOT Parallel Calligraphy Pen Set, 3.8mm Nib with Black and Red Ink C – toolsofwriters
PILOT Parallel Mixable Color Ink Refills for Calligraphy Pens 12 Colors NEW
27110 Zebra Pen BCA F-301 Stainless Steel Ballpoint Pens
Pilot Parallel Pen Ink Cartridges, Pilot Parallel Pen Black
A specific formula only intended for use in the Pilot Parallel Pen. Although it will fit in other Pilot fountain pens, it is not recommended to use in
Pilot Parallel Pen Cartridges - Box of 6 Black