Size - Mail Lite H/5 (270 x 360mm) Mail Lite envelopes are a practical and lightweight envelope that have a tough kraft outer that allow labels to be stuck on firmly and are also easy to write on. Mail Lite bubble envelopes are lined with an AirCap® barrier which is specially sealed for extra protection. They also have a self-seal strip, found on the flap this can save plenty of time if in a busy office atmosphere.