The PAR (Photosynthetically Active Radiation) Sensor reports the Photosynthetic Photon Flux Density (PPFD), which corresponds to micromoles of photons per meter squared per second (μmol m^-2 s^-1). This is the power of electromagnetic radiation in the spectral range that is used by plants for photosynthesis (370 – 650 nm). It features a waterproof sensor head and can be used to measure PPFD from sunlight and electric light sources. This sensor is ideal for experiments investigating photosynthesis and primary productivity and can be used in many agricultural and environmental science applications.