Milwaukee PH51 PRO Waterproof with 2 point Calibration and Replaceable Probe
Milwaukee Mi56p Replaceable electrode for pH55 and pH56 pH/Temperature Meter : Industrial & Scientific - Amazon.com
Weedness Milwaukee Replacement Electrode MI56P for PH55 pH Meter Replacement Part Minus Plus Pool Tester Aquarium Test Strips Meter Indicator Digital : Amazon.de: DIY & Tools