Harvest Keeper? Heavy Duty Multi-Use Storage Bags are the thickest and most durable bags on the market today. With a 1 mil thickness, these bags are puncture free, provide a strong odor barrier and will preserve your favorite foods natural flavors and color. The storage bags measure 18 in x 20 in and are manufactured for multiple uses. These bags can handle the heat which makes them great for use with ovens, microwaves, pans and slow cookers up to 400?F. They can also be used in refrigerators and freezers. Proudly made in the USA.