To even find out that one of these things is called a pin backing!

There are many words for them, but this makes most sense to me. The little nubbin’ that’s quite annoying to lose, you know the one. You drop it and it’s gone. These ones will be either black or yellow – shouldn’t matter because they’re not visible with the pin attached. Different colour, same job!

Buy a new one here if you lost one. These are made out of tough silicone, and they’re my favourites.