I prefer the hard enclosed binders because they stack well, and as Gerald says, they are the right width for negative sleeves.  Freestyle didn't have the ones I was looking for, but that was a good idea - I didn't check them.  I don't know what the ring size is, but am more interested in the thickness of the actual binder.  Printfile used to make ones that were around 1" thick - they were great for storing a small project in.  They were this style:
The Besfile ones only come in one thickness that I can see, around 2".
Sometimes you find them at the local camera trade shows, but I was hoping to find an online source for them.