Smooth, square white All Board Envelopes, measuring 249mm x 352mm and designed to meet Royal Mail’s Postage in Proportion price guide. These smart-looking board envelopes are produced using premium grade 500 micron, 350gsm, GD2 fully coated chipboard. They feature an easy-to-use peel and seal strip on a pre-folded flap so they close easily. They are the trusted method for keeping paper, card and thin items safe and in good condition during transit. Labels stick well to the smooth outer and you can also print directly onto them.