The perfect tool for taking scaled measurements from blueprints, maps, and plans. Select the built-in scale factor to match the plan, roll the PlanWheel and the measurement is displayed instantly. Features 111 built-in and thousands of available user-defined scale factors. Includes all common scales including Imperial and metric. Calculates square and cubic dimensions for regular areas and volumes. Counter and adder buttons on probe tip count items or add fixed lengths while scaling. Create, store, and retrieve two user-defined scale factors. Automatic shut-off assures long battery life. Protective case sold separately. Requires two AAA batteries (included). This PlanWheel cannot be interfaced with a computer.