What can I say about the Staples (R) medium metal binder clips black 1 1/4" size with 5/8th" capacity by staples that has not already been said? They bind up to 5/8ths of one inch and if you try really hard you can squeeze 11/16th of an inch in some of them....just be careful.
These are great little clips. Even better price when they are on sale. I use them for so many things. Chip bags etc. cheaper than buying the ones for them. Also great to put on a open single bag of milk it doesn't spill when taking it to a pot luck and bringing it home. Great for paper work too. Found a coupe in the box that didn't work properly they were squished..
These binder clips are great. There are brands that are more expensive but why pay more when the Staples brand gives you the same functionality and they can be used many many times. They are much better than paper clips since they don't get stuck to other papers and are easy to use. Also unlike rubber bands they do not wear out or tear the papers. This size is perfect and I use it the most. The other sizes are good for larger (or smaller sizes of papers) but this is the most user friendly versatile clip on the market. Buy lots!!