1This meter is a precision instrument measuring the intensity of sunlight. 2There are two units that can be selected: W/m and Btu. 3It supports maximum value hold function and data hold function. 4Measure directly without adjustment, steadily measure for a long period. 5Widely used for solar radiation measurement, solar energy research, meteorology, agriculture, physical and optical experiments. Features:This meter is a precision instrument measuring the intensity of sunlight. There are two units that can be selected: W/m and Btu. It supports maximum value hold function and data hold function. Measure directly without adjustment, steadily measure for a long period.Widely used for solar radiation measurement, solar energy research, meteorology, agriculture, physical and optical experiments. It can also be used to measure the light transmission intensity of glassto verify the performance of the glass, for example, car windowperformance test. Specification:Model: SM206 Resolution: 0.1W/m, 0.1Btu/(ft-h) Range Error: (10%R+2dgts)R: readings Temperature Error:0.38W/m/[0.12Btu/(ft-h)/]deviation at 25C Display: 4-1/2 LCD display, maximum display numerical value 19999 Overload Display: "OL" Shift: <1.5% /year Measurement Range: 0.1-1999.9W/m, 0.1-1999.9Btu/(ft-h) Sampling Time: 2.5 seconds/time Operating Temperature and Humidity: 0~40, <80%RH Storage Temperature and Humidity: -10~50, <70%RH Battery: 9V battery (NOT included)Size: Approx. 132 x 60 x 38mm / 5.2 x 2.4 x 1.5inWeight: 325g / 11.5oz (approx.)Package list: 1 * Solar Radiation Measuring Instrument (battery is NOT included) 1 * User Manual 1 * Packing Box