I recently received some parts to be plated that were sent Regional Priority Mail. This was the first time I had seen this so I checked into it on the USPS web site. It is a newer way to ship and is less expensive than Priority Fixed Rate boxes. Somewhat difficult to find information but it is part of USPS Click-N-Ship. You can not get the boxes from the post office. There are several differrent size boxes and they have to be ordered (free) on-line and USPS delivers them. You have to use USPS Click-N-Ship to print the labels. I have not compared all the rates but the shipments I have made are a few dollars less than Fixed Rate Priority Mail. The price varies depending on where it is being shipped but it is another option for shipping.
Dennis Hallworth
The regional rate boxes are somewhat smaller than the flat rate ones, but the shipping rates can be much lower for destinations within a few hundred miles or so. Most phones will not fit into the regional rate boxes.
Larry