Attach the key to the key ring without difficulty
Do you know the sometimes terrible fumbling, if you have to attach a key to a key ring?
Often enough, even a fingernail has broken off.
Much easier it is with a very simple trick or tool:
You simply use a binder! You put it on the key ring and press it together. So it pushes without effort, the metal spiral of the key ring apart and can push the key injury-free.