Colors vary enough between tiers to be usable. Note that this is a wide range of peroxide levels, often more than typical spa use, but if you need to locate higher levels this will do! It would be nice to have more intermediate levels defined by the color on the bottle, but it can still be used.
TDS water quality tester - TDS water hardness meter (portable digital salt meter for water analysis)
9 Review
Portable digital multimeter with sound continuity and thermocouple (electric tester) LTX DT-838
7 Review
Efficiently Test Your Antifreeze And Battery Acid With A 3-In-1 Refractometer
18 Review
Accurate And Versatile Digital PH Meters For Food, Brewing, Hydroponics, Pools And More!
7 Review
π¬οΈ Advanced 3-in-1 Indoor Air Quality Monitor with CO2/RH/Temp Data Logging and Audible Alarm - NDIR Sensor Technology
8 Review
π§ UEi Test Instruments DAFM3B Digital Multimeter
6 Review
Digital multimeter RGK DM-12
6 Review
Portable Handheld Manometer π for Accurate Pressure Differential Measurement
5 Review