This is a very good add-on and the only one close to what is needed for USPS. I would like to revive this thread. I have this installed on an oscommerce v2.3.4 with Mini Template System, Absolute pricing and some other stuff. It works well and the boxes are packed correctly but USPS doesn't seem to use the dimensions for the box it is packed in as shown in "Shipping boxes used" with the 'use product dimensions' selected. I have painstakingly installed and verified that it is installed correctly and it all seems to be working correctly otherwise. The reason I know its isn't working is because usps keeps offering first class letter and large envelope for items too large for those dimensions. Anyone else have this problem?