The envelopes are super we use them on our monthly billing to our customers. They are very professional looking and we are very proud to use this product at our company.
I have my stationery blocked off so a normal three part fold with the top side out shows the name and address of the person I am sending a letter to. So the process of sending a letter is educed by two steps. I do not have to retype the addressee and I then do not have to feed an envelope through my printer. I simply write my letter fold it accordingly and stuff it in the window envelope. My estimate is that this saves approximately a full minute for each letter mailed. This may not seem like much but this adds up with the volume of mail I deal with.
We use these envelopes mostely to send out invoices at the beginning of each month. By using these it saves time by not needing to type an envelope with our clients name and address. These are so convenient. Would be lost without them.