Problem is they only half seal. All are the same so tape is required on each one before mailing. I have ordered these many times and they were always better. Most of them sealed adequately and this is the first box that was really a problem.
Bottom of the bottom window needs to be about 1/4" higher up from the bottom of the envelope. The "memo" line shows and if you have account numbers in that line it can cause the post office to return the letter to you as undeliverable.
My office uses these envelopes for billing. They are a cost effective way of getting the bills to the right people. You have great help at your Store on Clippert & Michigan Ave Lansing MI
These envelopes might work OK if you are only sending a check but using an 8 1/2 x 11 document folded so that address shows in window does not work. The gummed part sticks to the paper and ends up causing the document to be ripped when it is opened.