Stanley 0-77-018 Ultrasonic Distance Meter automatically calculates area and volume The Stanley 0-77-018 allows one person to measure up to 12 metres without assistance. The Meter has an intuitively designed toggle button featuring three measuring modes: length, area, and volume. It has a large, easy-to-read LCD screen which can display the last three measurements for quick reference. Features: Accurate measurements (+/-0.5%) you can rely on Automatically calculates area and volume Manual addition mode for specialized calculations (i.e., perimeter) Requires 9 Volt Battery (not included) Specification: Range: 12 metres / 40ft  Accuracy: ±0.5% Dimensions: 140 x 65 x 40mm