United States Postal Service Ps311 30-Lb Digital Calculating Scale With Usb Pc Connection & Software 30-lb Large Capacity. This scale does not does not have to be connected to a computer to work Large 5-digit LCD Display 3-way Power: USB, Battery Or Adapter Can Be Used With Online Postage Services Hinged Platform Allows For Weighing Of Large Envelopes Or Mailing Tubes 30-pound capacity postage scale Measures from 0.1 ounces to 30 pounds Can be powered via a 9-volt battery, USB connection, or AC power adapter (not included) Mechanical overload protection Can be used with online postage services