5 Star C5 Window Pocket Envelope Press Seal 90gsm 229x162mm White (Pack of 500) 6525165 Star white C5 pocket envelopes. These envelopes are made from lightweight 90gsm paper and feature a window, allowing you to clearly display the address of your correspondent. They feature a press seal, meaning that all you have to do is apply the two glued flaps together to form an instant bond. This pack contains 500 envelopes. C5 size Made from lightweight 90gsm paper Window size of 100x40mm Window position 65mm in from left hand side, 25mm up