The boxes that I use and I assume all of us use are the 8 3/4 X 4 1/2 X 2 which isn't listed on the USPS Flat Rate list. The closest is a 5 3/8 X 8 5/8 X 1 5/8. These are pretty close but I just wanted to hear from someone that has used this before and can verify this will work.
Thanks,
Mark
Thanks,
Mark