Both the BROAD (black and white barrel and black lid)
and the MICRO (fuschia barrel with orange lid OR aqua blue barrel with lime green lid) have  black fade-proof, water resistant and tamper-proof ink.
 
Revolutionary air-tip releases ink depending on pressure, creating a variable line width.
 
The uni-ball Air rollerball pen writes with the look of a fountain pen but with the ease and portability of a rollerball.
 
Because it is waterproof these pens are excellent for Zentangles, doodles, drawing, pen and ink etc.
 
A rollerball pen unlike any other that has a varied line width depending on the pressure applied to the tip
Offers a smooth and light writing experience
An extremely smooth writing experience by minimising writing friction
 
 
 
The BROAD gives a slightly wider, heavier-looking line, and the MICRO delivers a thinner line with absolutely no scratchiness or skipping.