An envelope with a flap made for a payment or a reply. The flap is larger, so a return address, a short form, or a remittance line has room. It is the envelope that comes back, not just the one that goes out.
Keep the form type large enough to read after the flap is folded. The inside of the flap is where that short form usually sits.
Upload the art with the order, or send the file after checkout. We send a digital proof before anything is printed.
