Feature push-button calibration and high ±1% full scale accuracy! Waterproof, dust proof housing that floats is certifiable to IP67 standards - Replaceable sensor lets you reuse same meter body, saving you money - Automatic Temperature Compensation - 0 - 1990 PPM - Hold function, Auto-Off Our waterproof microprocessor TDSTestr basic offers push-button calibration and ±1% accuracy in a rugged waterproof housing. Never worry about losing your tester in a pond or tank; these testers float!