The Oakton ORP 50 Waterproof Testr features a replaceable double-junction platinum electrode — ideal for checking dirty water, heavy metals, sulfides, and organics. Valox®electrode body resists most chemicals. Use these versatile instruments for applications ranging from swimming pool testing to pulp bleaching. Meter features 2 mV accuracy and a +/-150 mV offset. Housing allows you to attach a lanyard (included) for easy retrieval. Additional features include a hold function, auto-off function, self-diagnostic error messages, and a three-segment battery-life indicator.