Uni-ball says this is the world's favourite pen for over 10 years. It's not surprising as it's a really good pen.
It's a slim pen with matt surface cap and end. You judge the colour of the pen by the cap.
When you uncap, you get to see the transparent ink feed system which is cool.
The body has a see through section that allows you to see how much ink is left. This pen uses liquid ink.
The Uni-ball eye is available in two line width, Micro 0.3mm (0.5mm ball) and the Fine 0.5mm (0.7mm). The product code for UB-157 or UB157.
The tip is made of stainless steel with tungsten carbide ball.
The pens come with 10 colours, namely Black, Blue, Red, Green, Orange, Pink, Light Blue, Violet, Light Green, Wine.
The ink used here is the Uni Super Ink, a type of pigment ink.
It's waterproof, fade-proof, acid-free and light resistant, and hence of archival quality.
It's specially formulated to bind with the paper, to prevent criminal check washing and document alternation.
It writes smooth, dries fast, does not skip, blotch or feather. The black is very black.
I use the pen for watercolour sketches and it works extremely well. When I spray my artwork with fixative, the ink stays as it is, does not break down, and retains the intensity of dark.
Lines are from the Uniball Eye and ink wash with Daler Rowney Kandahar black ink.
Note the only the Black, Blue and Red feature the waterproof pigment ink.
Uni-ball Eye vs Vision
The Uni-ball Eye also seems to be marketed under the name Uni-ball Vision. From what I can see, the design of the pens are almost identical except for the names printed on their bodies.
This is a high quality pen that's suitable not just for writing but drawing as well. For sketching, I would bring at least two just in case one runs out of ink.
You can also probably find it at Jackson's Art Supplies (UK)