7 Hole Sheet Protectors
One of the issues with standard 3 hole sheet protectors is that they do not always fit all binder in particular 2 and 5 ring binders. That is why universal 11 holes sheet protectors which also covers the 7 holes which is needed for many government tenders. The US government request as minimum the 7 holes as to cover all the different type of binder used by the government.
If you wish to know more about 7 hole sheet protectors look at the attached link.