I bought these refills in blue, black, and red for my uniball jetstream
multi-pen. None of the colors perform as expected. I use this pen daily at work,
and have found that after only 25-50% of the cartridges have been used, the ink
loses its color intensity and begins skipping. I am replacing ink much more
frequently than should be necessary. I will continue to use until my stash of
refills is exhausted (since the money has already been spent), then will trash
the pen. Do not recommend, will not repurchase.
I really like the 0.7mm ink better than the 0.5 because it seems to write
smoother and is more legible. I had a previous problem with the refills being
too long for my Uniball Jetstream but these fit perfectly.