Oakton PCTS Testr™ 50 WD-35634-35 Waterproof Pocket pH/Cond/TDS/Salinity Tester is great for water, wastewater, laboratory or plant use, these multiparameter testers feature long-life pH electrodes with a wide range of sample compatibility. Combines measurement capabilities of three testers in one convenient pocket-sized unit. Pin-style conductivity sensors feature stainless steel electrodes for chemical resistance and durability. Replaceable sensor module saves you money by reusing the meter body. Up to 3 point pH calibration with NIST or USA auto buffer recognition.