This unique document holder can provide the same level of protection as other heavyweight sheet protectors, but without the pre-punched binding edge. If documents are to be stored loosely instead of in a binder, this storage option has a much cleaner overall appearance. Use them to protect frequently used materials or to post signs and notices. Top-loading polypropylene sheet protectors are made of extra-durable heavyweight polypropylene, and they're manufactured acid-free to prevent photocopy transfer.