For the record, I don't ever use the cardboard staple holders for anything. I just go ahead and spend the extra to get mylar flips...for a number of reasons, but the most important being:
1. they are completely reusable.
2. no staples to damage the coins.
3. no staple rust to damage the coins.
4. you can put whatever you want on the insert, and you have 2x2 inches to write it.
5. you can use whatever color paper you want for effect (or for other reasons).
The cardboard holders are about 2.5 cents each in bulk. Mylar (non-PVC) flips are about 4.5 cents each in bulk. I ALWAYS just spend the extra cash and do it right the first time. All the hogwash about flips scratching coins is just that...hogwash.