TL;DR: DO NOT BUY!
I love my Lamy Safari rollerball pen, but the quality of these refills has made me rethink using it as my everyday writing implement.
I received the pen as a gift a year ago, and used it everyday for several months. The insert in that first one worked well and lasted a long time. When that insert ran dry, I ordered this set of 3 refills.
Only one of the set has worked flawlessly. The other two had spotty performance and could not be depended on to be able to write whenever I needed it.
For the price of these refills, at almost $5 apiece, I expect a far better writing experience than a cheap drug-store pen. Unfortunately, whatever cheap ballpoint is knocking around my desk drawer is far more dependable and usable than Lamy's M63 refill.
I can't in good conscience recommend these.