The Watts Up? Pro has internal memory to handle over 2,000 records of data. It also comes with software and a USB interface. The software automatically graphs all the data and includes a Payback Calculator so you can tell how long it will take for a new energy efficient appliance to pay for itself.
As a data logger, the Pro model records all the data into non-volatile (stored even if power is lost) memory. Over one thousand data points can be stored, starting with a sampling rate resolution of one second. The sample rate is user selectable or can be automatically set (resolution decreases over time) so ears of usage can be accurately recorded. The included USB connection and software allows quick download of data to a PC. Data and graphs can also be exported to popular spreadsheet and word processing programs for further analysis.