Strong self seal adhesive strip. Once sealed, stays sealed. Completely opaque. You cannot see through whats packed in the bag Lightweight - Saving you money by reducing postage cost Waterproof Top Quality Extremely lightweight allowing you to minimise postal costs. Produced using co-extrusion technology and manufactured from 50-60 microns thickness (220 -240 gauge). Compresses 3 layers of polythene film into one making them very robust, opaque, and durable. 100% moisture resistant. Puncture and tear proof, making them able to withstand rough handling. Tamper evident and provides high confidentiality during transit.