Calculated Industries 6335 Scale Master ProXE Advanced Digital Plan Measure with PC Interface 91 Built-in scales for more versatility, 50 imperial (feet-Inch) and 41 metric 10 Custom Scales, 3 each for imperial and metric units, lets you "roll" or define any scale from plans that are out-of-scale. Permanently store new scale for future use Constant (+K) allows you to add/subtract a constant value to a distance measured for take-outs and add-ons. Calculate area, volume, height, length, width for imperial/metric units Built-in Auto Counter to count how many times a pre-set distance has been rolled. Manual Count while rolling for studs, outlets, or other items. Subtract function to remove the last distance measured. Includes 2 long-life 3-volt batteries, hard cover protective case, English User Guide, 15-Feet PC interface cable with plug-n-play connectivity