The MQ-500 meter from Apogee Instruments is a handheld meter for measuring PAR/PPFD levels in various environments such as greenhouses, indoor grow areas and aquariums. It has manual and log modes, stores measurements and records daily light levels. With an accuracy of ± 5% and a measurement range of 0 - 4000 µmol × m -2 × s -1 , it is ideal for monitoring light levels for plant growth.