shipping bags.  Only for non frigle items UCGOU  poly  mailers 19x24 inch white 49 pack extra large shipping bags envelopes are made of heavy duty 100% virgin plastic which have a good stretch lightweight and water and tear resistant the poly bags is light enough not to add too much to weight in first class packages but thick enough to feel that your products are safe when inside However the most important is the poly mailers are only suitable for no frigle items or soft ones like clothes