Rozway Premium Pocket Size pH Meter.  Range: 0-14.0 pH.  Resolution: 0.01.

You can use a pH meter to check the pH of your water, mash, [test Star San effectiveness] and finished beer.

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Rozway Premium Pocket Size pH Meter Digital Water Quality Tester for Household Drinking Water, Swimming Pools, Aquariums, Hydroponics, pH Measurement for 0-14.0 pH, High Accuracy, 0.01 Resolution