You don't have to break the bank to acquire a quality photosynthetic active radiation (PAR) meter ... affordable models can be just as effective. In side-by-side reading comparisons, the SpotOn Quantum PAR meter was just as accurate as a more expensive, laboratory-grade unit. Designed for greenhouse, field and R&D applications requiring reliable plant growth light readings, this meter measures PAR light indoors and outdoors regardless of source ... from full sun to fluorescent.