Product Self Sealing Grey Opaque Poly Postal Mail bags  Quantity and Size Multi Listing please select from drop down list above what size and quantity you would like Guarantee Other This superior range of strong lightweight grey mail order mailing/postal bags have been designed to provide quality, security and performance that you can trust. The high specification of grey film has been chosen to give the best performance to weight ratio, whilst reducing your postage costs, but ensuring delivery of your products in good condition. With a unique grade of hot melt glue used for sealing the mailing bags, once they are sealed, they are sealed! Mailing Bags can be addressed and accept labels, stamps and biro. These are opaque for security of your items.