https://www.amazon.com/Oakton-EcoTestr-pH-Pocket-Meter/dp/B01MYV3938/ref=mp_s_a_1_1_sspa?keywords=oakton+ph+meters&qid=1565381660&s=gateway&sprefix=oakton+&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyNUE2VzlINTEyWFQ4JmVuY3J5cHRlZElkPUEwMDQ5MjAwT1NOV1MzMjFTSVhFJmVuY3J5cHRlZEFkSWQ9QTA0ODk2N...