Fresherpack's premium quality mylar zip lock foil bags are smell proof, moisture proof and light proof. Premium quality? Yes, they are 5.1mil thick (most other sellers are 3mil) meaning they are not see throught like others and have an extra strong zip lock; perfect for herbs, food and non-food products, supplements, tea samples. Plus a handy tear notch for easy opening without needing scissors. Easily heat sealed above the ziplock. Big range of sizes and colours.