I picked this one up JetPens last year, but I just now got around to reviewing it. What struck me as interesting about this one was the .3 rollerball refill and the ability to use brush refills, too.
The barrel and brush refills come in a variety of colors, or you can use a .3 rollerball refill in black, as I opted to do for my configuration.
The refill has a plastic comb inside similar to uniball and Pilot liquid ink pens, so everything is business as usual in that respect. I tend to write small, so I was excited for the micro point rollerball. I wasn't as excited after using it due to the performance...
What bothered me the most was the inconsistency in ink flow. At times the line would be thin and the ball was dry and somewhat scratchy. The ink would then start flowing and leave thicker lines on the page, which made the think lines seem even thinner.
If you look at the word 'inconsistent', you can see how the letter 'I' is faded at the top and thicker at the bottom.
This pen is called the ZIG Letter Pen, and I cannot say that I would recommend using this for writing a letter at all. I think the brush refills might work well for calligraphy, but I have not tried them as of yet.
Given the ink flow issues on the rollerball refill, I am not a huge fan of the ZIG Letter Pen, but I think it might work well for sketching. Sparkles or not, I wasn't dazzled with this one.
Kuretake ZIG Letter Pen Body - $2.50 at JetPens
Kuretake ZIG .3 Rollerball Refill - $3.30 at JetPens