Milwaukee waterproof TDS tester 

Model T76: Professional, easy-to-use waterproof handheld high-range TDS tester, made by Milwaukee Instruments. 

The Milwaukee T76 gives you automatic temperature compensation for accurate results. It has a battery life of 250 hours of continuous use. Takes three (3) 1.5V batteries which are included.

The Milwaukee Sharp T75 offers a replaceable electrode (part #MA73076) for long life.

Specifications:

Range: 0 - 9990 ppm
Resolution: 10 ppm
Accuracy: ± 2% full scale
Calibration: Manual 1 point
Electrode: Replaceable MA73076
Temperature Compensation: Automatic 0 - 50°C
Battery Life: 250 hours of continuous use
Battery Type: 3 x 1.5V
Environment: 0 - 50°C / 100% RH

The Milwaukee T76 includes a protective cap, hard carrying case, calibration solution, batteries and instruction manual.

Two year warranty on tester. One year warranty on probe.

More info from the Manufacturer (PDF format - Lots of detail.)