LightScout DLI 100 Light MeterSimple, one button operation Displays light intensity levels every 4 seconds for 24 hours An affordable, first step in measuring light Measure PAR light (Photosynthetically Active Radiation) With the push of a button, the meter runs for 24 hours and calculates your Daily Light Integral (DLI) Real time intensity levels are shown every 4 seconds in mol m 2 s 1 Battery included; water resistant