Smooth white All Board Envelopes, measuring 164mm x 239mm – designed to meet Royal Mail’s Postage in Proportion guide. They are made using premium grade 500 micron, 350gsm, GD2 fully coated chipboard, with an easy-to-use peel and seal strip on a pre-folded flap. You can trust these board envelopes to protect paper, card and thin items during despatch. They can reduce time-spent processing items as they include fast to use peel and seal strips on a pre-folded closing flap and you can print directly onto the coated surface or use a label.