Scalex Planwheel SA2 Features include - 111 built-in and thousands of available user defined The scale factors includes all common scales â€“imperial and metric. Calculate auto-scale factor from reduced, enlarged or odd-scale drawings. Measures in inches, feet, yards, miles, centimeters, meters, and kilometers. Calculates square and cubic dimensions for regular areas and volumes. Counter and adder buttons on probe tip let you count items or add fixed lengths as you scale. Create, store and retrieve user-defined scale factors. Clear, audible tone indicates wheel movement. Automatic shut-off assures long battery life. Low battery indicator. Plus minus (+-) mode allows user to simply back-up to deduct an over-rolled measurement. Need a tool to quickly quote and estimate for building and construction then look at the SA2 Scalex Planwheel.