These covers may afford better protection by virtue of their design. They have two flaps which fold in, and have 2 score lines spaced 1in. apart on each side. The advantage to your collection comes from the added protection offered to mounted specimens. They are offered in .010 non-buffered, .010 Lig-Free I, and .012 MicroChamber papers. Large sheets (17 x 34.5 inches) fold to a finished 17 x 12 inches (California type).