The new OS5p is the latest addition to the ADC:OSI range of Chlorophyll Flurometers. Weighing just 1.4Kg and offering 20 hours of continuous use, the battery operated OS5p is set to offer new levels in portability and performance for a field pulse modulated flurometer. Both ambient light and dark adaptation parameters may be determined by the OS5p including Fo, Fm, Fv/Fm, Y, Ft, Foq, Fms and OJIP transients. Photochemical and non-photochemical quenching coefficients such as qP, qN and NPQ can be calculated. The OS5p offers researchers exceptional control over each experiment. This includes source intensity, saturating pulse and a sampling rate of up to 1 million samples a second. A two channel (660nm / 450nm) modulating light is provided as is a 735nm LED for Fod determinations.