RPI Large Display pH Pen, 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.