These unique pouches are composed of Biaxial oriented nylon or BOPA. Compared to our standard poly plastic blend, BOPA has higher tensile strength, higher elasticity, and greater temperature control capabilities. The characteristics of these bags allow them to function in subzero temperatures, making them perfect for frozen foods or other frozen products. When the bags are heat-sealed, they will become completely waterproof. The clear walls of the bag allow the stored products to be seen, and the secure zipper allows the bags to be resealed after opening. The sturdy gusset supports the pouch and increases the internal capacity. By now you should see that these bags have more than enough benefits to warrant trying them out for yourself!