The only possible wording you can really do... is something about insulin. They sell pins exclusively for diabetes there, nothing else (in my area, yours may be different).
I told them is was for insulin, and was looking for 25 guage. They said they didn't have any, and pushed getting 28/29 guage. Smallest they had was 27 guage Micro-Fines. I just took those and stopped arguing, since I needed some slin pins anyway. I was originally looking for 25 guage for something or other... never found them anywhere (Wal-Mart, Walgreens, etc.). Just ended up ordering them.