I really like the "Staples® Heavy-Duty Sheet Protectors by Staples" because not only do they have many uses but they are also reusable and if they should ever wear out they can be recycled. I usually buy them in the greatest quantity per box because they are each less expensive then. The "Staples® Heavy-Duty Sheet Protectors by Staples" are great when used to protect important documents. In addition I find they are unsurpassed in protecting genealogical documents and pictures. As a collector of "first day covers" I wish "Staples® Heavy-Duty Sheet Protectors" were manufactured to hold in place more than one first day cover per protector. Lastly Sheet Protectors manufactured with a red tint would be helpful to quickly identify the "really important 'stored' documents" and/or current papers with a high priority to work.
Very hard to open the first time use. Other than that they are very good protectors. Can easily fit two sheets of paper in each protector and that is what I need.
I use sheet protectors to store music that I pull on a regular basis. I've tried using flimsier sheet protectors but quickly determined that they were not worth the money. These are a quality weight allowing you to fill them with minimal effort and they last for years.