Use the PlanWheel-SA for taking scaled measurments from blueprints, maps and plans. 52 built-in and 3 user-defined scales. Calculate any custom scale from reduced, enlarged or odd-scale drawings. Measures Kilometers, meters, centimeters, miles, yards, feet, inches. Calculates square and cubic dimensions for regular areas and volumes. 2 AAA batteries included. This unit can't be interfaced with a computer. Call for price on Planwheel-XLU2 and XLU2 interface kit (sold serperately).