5 Star C5 Pocket Envelope Peel and Seal Window 100gsm 229x162mm White (Pack of 500) 9066245 Star white C5 envelopes. These envelopes have a blue opaque interior for security and are made from mediumweight 100gsm paper, making them perfect for everyday use. They also feature a window which allows you to clearly display the address of your correspondent. C5 size 229x162mm Made from mediumweight 100gsm paper Window size of 100x45mm Window position 60mm in from LHS, 24mm up Peel and seal closure peel away the release tape from the flap to