Sper Scientific 850050 Waterproof Large Display pH Meter Pen, 2-12pH Range, 0.1 Resolution

Highly stable and accurate readings with a large LCD display. Designed for simple one-hand operation. Automatically calibrates to pH 4, 7, 10 buffers and can be adjusted to recognize non-standard buffers as well. Features hold function, and auto power off with low battery indicator. The case is IP65 waterproof, and will float if accidentally dropped into the water. Comes with 4 button-cell batteries and a built-in electrode kept moist with a protective cap