I also have an electronic meter so I can determine how accurate these paper indicators are. They fit the "strongly alkaline, weakly alkaline, weakly acidic, strongly acidic" scale, but that's about it. Forget about using them to see if you're close to neutral or some other quantitative pH.
π― Honey Refractometer with Automatic Temperature Compensation (ATC) - Tiaoyeer Moisture, Brix, and Baume Refractometer for Honey, 58-90% Brix Scale Range - Honey Moisture Tester
31 Review
Portable digital multimeter with sound continuity and thermocouple (electric tester) LTX DT-838
7 Review
Digital PH Meter Tester - Tiaoyeer Water Quality Tester With ATC, 0.01PH High Accuracy, 0.00-14.00 Measurement Range, 0.01 Resolution For Drinking Water, Aquarium, Swimming Pools, Hydroponic
8 Review
Accurate And Versatile Digital PH Meters For Food, Brewing, Hydroponics, Pools And More!
7 Review