Features 1This meter is an accuracy 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. Specification Features: This meter is an accuracyinstrument 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 glass to verify the performance of the glass for example car window performance 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 1.5in Weight: 325g / 11.5oz (approx.) Package List 1 * Solar Radiation Measuring Instrument (batteryis NOT included)1 * User Manual1 * PackingBox