A: Yes, Both UPS and USPS shipping plug-ins pull out exact shipping rates for each of the respective shipping services from the supplier's website (i.e. UPS or USPS). First, shopping carts collects information about the order, such as weight of the order, originating and destination zip codes (or countries and postal codes) and sends it to either UPS or USPS website. In turn, shipping carrier websites provide matching shipping rate that is automatically inserted into the order along with the information on the type of the selected shipping service. IF both UPS and USPS are activated under shipping plug-in settings, customers will be able to chose either one of the shipping carriers.