Smooth white All Board Envelopes measuring 125mm x 125mm they are square and smart-looking made using premium grade 500 micron, 350gsm, GD2 fully coated lined chipboard, with super high tack adhesive peel and seal strip on a flap, for easy closing. These cardboard envelopes are a great way to keep paper, card and slim items safe during transit. The coated surface has excellent bonding properties, making it perfect for printing on to and for sticking labels.