Oakton® Waterproof Multiparameter Testr 35 Series Pocket Meters combine up to five measurements in one pocket-sized meter. Determine pH, conductivity, TDS, salinity, and temperature. Great for water, wastewater, laboratory or plant use. Push-button calibration allows you to calibrate more precisely than trimpot adjustment; no screwdrivers necessary. Automatic temperature compensation (ATC) gives you accurate readings even with fluctuating temperatures. Waterproof, dustproof housing meets IP67 rating, plus it floats! Hold function freezes reading until you can record it.