I usually like clips on my pens/pencils for two reasons. Firstly so they don't roll off into the distance (which is a problem with the
very smooth finish of the Fisher Space Pen) and secondly just because I like the
asymmetrical look of it.
The problem with this (that I was aware of before buying) is that it truly
doesn't stay on the pen. Sometimes when I squeeze it in place really hard it
stays for a few days to a few weeks (depending on how much I use and handle the
pen) but it's far too easy to remove by simply being in my pencil case.
If it would just stay on, I don't see why I wouldn't give this 5 stars.
After some experience carrying around Fisher bullet Space Pens, I wouldn't
really trust these clips completely for shirt pocket carry. Unless you check
the snugness of the clip regularly, it will slowly work its way loose, and fail
when you least expect it. On the other hand, it's great for keeping your pen
from rolling off a table.