These heavy duty white opaque Postsafe polythene envelopes are made from 100 micron polythene, but look and feel like paper. Lightweight and super strong, they feature a secure peel and seal strip to ensure reliable and easy closure and are weatherproof, burstproof, tear and puncture resistant. The paper-like surface on these polythene envelopes is easy to write on and easily accepts stamps, labels and franking. Super strong, 100 micron Postsafe polythene envelopes are also super environmentally friendly and 100% recyclable.