Along with being 100% waterproof and airtight like the aLoksak, the Opsak (Odor Proof Sak) is also a 100% odor barrier bag. The same seal is used on the Opsak as the aLokSak – no gusset – but with a different film that is odor proof and FDA approved. You can store food undetected to bears and other pests in your campsite by sealing them in the Opsak. Also, because the Opsak is FDA approved, you can use it in food preparation. You can even pour boiling water into the Opsak because of its extreme heat resistance. This Opsak measures 7" x 7.75" outer dimensions (6.75" x 7" inner dimension). Each package contains two bags. 100% Odor Barrier Bag. Great for food transport and storage. Add boiling water to rehydrate food. Can withstand direct heat up to 170 degrees Fahrenheit. Certified waterproof up to 200 feet by SCUBA Schools International. Pack out body wastes.