The Bosch GIM Professional Incline Measurer measures precise tilts in degrees, percent or millimetres/metres. Direction arrows and audible signals at 0° and 90° enable easy alignment. Measured values automatically turn on the display when working overhead. Specifications: Measurement Range: 0 – 360° (4 x 90°).Electronics Measurement Accuracy: @0°/90° ± 0.05°, @1-89° ± 0.2°.Vial Measurement Accuracy: ± 0.057° = ± 1 mm/m.Units of Measurement: °, %, mm/m.Power Supply: 4 x AA 1.5 V LR6 Batteries (supplied).