Aloksak® bags are resealable element-proof bags featuring a hermetic seal. That means absolutely no water, air, dust or humidity permeates the closure. They are designed for a wide range of applications and environments. The transparent bags are flexible and puncture resistant. They come in multiple sizes and can be sealed over and over again. Certified waterproof to 60 meters (200 feet) and tested and approved by the US Navy Experimental Diving Unit. Temperature rated @ -40ºF to 140ºF, and constructed using medical-grade film that is FDA approved. These are great bags for packing gear in survival kits, packs, or anywhere you want your stuff to stay dry! You can also protect your electronic devices and cell phones can be used without removing them from the bag. They also float! We offer the following sizes. This pack contains 4 Aloksak® element-proof bags, 1- Each of the 5" x 4.75" outer dimensions (4.75" x 4" inner dimensions), 4.4" x 7.25" outer dimensions (4" x 6.5" inner dimensions), 6.5" x 6" outer dimensions (6.25" x 5.25" inner dimensions), and the 8.75" x 6" outer dimensions (8.4" x 5.25" inner dimensions).