This was currently £3.92 before getting over 500 degrees.
Now 12pence cheaper but still a great deal.
These bags help you meet the Large Letter size dimensions, so that [depending on the weight and overall thickness] you pay between 69p and £1.90 to send your small package!
Grey Postage Mailing Bags
Opening - 10" (250mm)
Length - 14" (350mm)
Self seal lip = 50mm
Thickness = 60micron