LION plastic binder envelope will fit all standard 3-ring binders. Binder accessories, such as this handy binder pocket, are great for keeping various loose materials right in your binder. With its expandable gusset, these plastic binder envelopes can hold up to one inch stack of letter size papers. Plastic envelope with velcro type (hook and loop) closure makes loading / unloading simple and keeps contents secure. LION clear plastic envelope is PVC free, archival safe, resistant to moisture & tearing.Made from recyclable & acid free polypropylene.