Double junction electrode is ideal for dirty water, heavy metals, sulfides and organics. You'll never loose this tester by dropping it into a tank or pond; the waterproof ORPTestr floats. IP67-rated housing protects the instrument from rugged field and plant environments. Push-button calibration lets standardize tester in calibration solutions, or making it agree with an established work standard. Replaceable sensor on ORPTestr 10 lets you reuse meter body many times without losing waterproof and dustproof protection. Large surface area platinum band sensor gives a faster, more stable response. ORPTestr BNC accepts any ORP electrode with BNC connector. Operates on Four 1.5 V batteries with an estimated 500 hours of battery life.