These archival Blue-Gray, Acid-Free Movie Poster Boxes are made from .060" thick, Perma/Dur® buffered board outside. The inside is lined with heavy, white, lignin-free bond paper that has a pH of 8.5. Drop front on the short dimension of the box allows for easy poster removal. Boxes come assembled and have metal-edged, reinforced corners for superior stacking strength and shape integrity. INDEFINITE STORAGE.