I wish there was an envelope size to match the letterhead. The letterhead dimensions are: 11"l x 8.5"w (standard letter size). It would be a great addition for both business and personal stationery—unless such a size already exists and I've just missed it!
Years ago, they had a ton of different envelope sizes. It looks like they got rid of most of them, but I agree that standard letter size would be a good addition to their lineup.
