Use for on-the spot pH readings with an accuracy of ± 0.1 pH. A series of fully immersible (waterproof to IP67) pocket pH testers called pHep meters (pronounced FEP) pHep 1 pocket pH tester with the benefits of a large LCD display which can be read from any angle, and rugged fully immersible waterproof, ergonomic casing which fits comfortably in the hand. Calibration is two point ( 2 buffer values 4.01 & 7.01 or 7.01 &