They were too small (diameter) for what I wanted to do with them. My fault - I tried some 6mm plastic end caps and they were a bit too big. So I decided to try these 5mm - and they are way too small for the holes I'm trying to fill. The plugs themselves are good, just a bit small. I think I can still use these as I have a couple of large bookshelves that have bolt holes for adjustable shelves - and I think they fit the unused bolt holes. Anyway, I'm happy with my purchase.