Measure, add, multiply, and compute the square and cubic footage of 1 room or a whole house, with just the press of a button. Narrow beam of sound waves bounce off solid objects back to the hand receiver. Computes and adds both area and volume. Measure from 1 ft. 6 in. up to 45 ft. Measures in feet/inches and meters/centimeters. Accuracy is 99.5% + or - 1/4in.. Comes with instructions pamphlet. Requires one 9 volt battery.