Our premium quality 2 mil, reclosable polyethylene bags provide superior clarity. Our zip-lock bags have heavy-duty zippers that prevent seams from splitting. Zip-lock bags offer good protection from dust and moisture for general-purpose storage. The polyethylene used to make our bags are 100% virgin polyethylene, chemically inert and free of coatings. Although our bags are made from the best materials, polyethylene bags should be considered for temporarily use only, not for long time archival storage. The standard 2 mil bags offers good protection. The opening end for each size of bag is the first dimension listed in the description listing.