Oakton's WD-35423-00 pH 1 EcoTestr is economical and easy to use. With its crystal clear, ergonomically designed display, you can easily view measurements at a glance. Each rugged tester has a waterproof and dustproof housing for use in dirty and damp field conditions. Simply dip and read - the orientation of the display means there's no need to turn your head or tilt the tester. Single-junction electrode is well-suited for general purpose applications. Recessed bulb with bulb guard protects against breakage. One point calibration with auto-buffer recognition for quick calibrations. Hold function locks in measured value. Auto-off function preserves batteries.