Sensors used the exclusive photo diode & colour correction filter, spectrum meet C.I.E. photopic. Separate LIGHT SENSOR allow user take measurements of an optimum position. High accuracy in measuring. Measuring ranges of 0-50,000 lux in 3 ranges. Internal zero adjustment. 13mm LCD display. Built-in low battery indicator. Operated on DC 9V battery, 006P, MN1604 (PP3) or equivalent