The YSI ProDSS (digital sampling system) is a portable water quality multiparameter instrument for the measurement of several critical parameters - dissolved oxygen (optical), turbidity, pH, ORP, conductivity, specific conductance, salinity, TDS, resistivity, TSS, ammonium, ammonia, chloride, nitrate, depth, temperature and GPS coordinates. Designed for use in applications such as surface water, groundwater, coastal/estuarine, and aquaculture the rugged and reliable ProDSS allows for the measurement of water quality parameters with digital sensors. The ProDSS uses smart, user-replaceable sensor technology that can be connected in any port and automatically recognized by the handheld while retaining the calibration data.