When aviation was first becoming popular in the early 20th century, people were able to write a letter and send it far away in a shorter amount of time. The highly recognizable airmail envelopes with different colored borders became a way for the post office to easily sort through international and domestic mail as different countries would have different colors on their airmail envelopes. These envelopes by Midori are a replica of the traditional airmail envelopes and we love their vintage look. 10 envelopes included Dimensions: 3.9 in (9.8 cm) x 7.5 in (19 cm) Envelopes for Airmail Letter Pad Medium andLargeenvelopes available WARNING: California\’s Proposition 65