Photo 1 of Apera Instruments GroStar Series GS1-P pH/ORP Pen Tester Kit with Replaceable Double-Junction pH Probe and ORP Probe for Hydroponics Water Quality Testing, Gen II

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Photo 1 of Apera Instruments GroStar Series GS1-P pH/ORP Pen Tester Kit with Replaceable Double-Junction pH Probe and ORP Probe for Hydroponics Water Quality Testing, Gen II