Zip-Close. Heavy Duty 6 mil. Plastic Bags. Archival Quality. These bags are 10 inches wide by 16 inches tall and the zip-closure is across the 10 inch way. This size allows a little extra room so you can slide our legal size river atlas's with binding on the 8 1/2" dimension to slide down into the bag. This item should be waterproof although we don't guarantee that it is 100% waterproof, these bags are really great! We have priced this at only a dollar each, so please add this item to your order if you want an awesome plastic bag to hold your atlas.