I have a particular pen that I use constantly, prefer it above all others(GONAVY!) but, like anything used, it ran out of ink. So I sought another, checking many other big box stores for this particular cartridge(Foray ballpoint refill, 2-pack), which has an outline to match printed on the package. No problems, easy to get the right one! However, I couldn’t get the cartridge to fit accurately, even though expert/professional/friendly/helpful assistant DEBORAH allowed me to try it. Without belittling me, she advised to take the little spring out of the barrel, which, of course, made all the difference. Then, when paying, I somehow managed to miss the actual checkout line, going to customer services instead. How good to see that I can post from this site, although I only wanted to buy the refill. They accomodated me extremely well, and I’ll be returning. I strongly suggest that you come here and explore all the many different options available that will make your life easier, too!