SCALEX PlanWheel SA 2™ - Here is the perfect tool for taking scaled measurements from blueprints, maps and plans. Just select the built-in scale factor to match the plan and roll the PlanWheel. The measurement is displayed instantly. Features 111 built-in and thousands of available user-defined scale factors. Includes all common scales - Imperial and metric, too. 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 2 user-defined scale factors. Automatic shut-off assures long battery life. Protective case sold separately. Requires 2AAA batteries (included). This Planwheel cannot be interfaced with a computer.