Oakton WD-35634-30 pHTestr 30 pH Tester, For Temperature Three-point, push-button calibration with auto-buffer recognition for a wide range of results Automatic Temperature Compensation (ATC) for accurate readings in fluctuating temperatures Unique, double-junction electrode design and increased reference gel volume for long electrode life in harsh environments Large, upright, dual-line LCD display screen for ease of viewing, and to display indicators Waterproof, dustproof housing that sits on a flat surface and the meter floats, if dropped in liquids