Apera Instruments AI311 Premium Series PH60 Waterproof Ph Pocket Tester Kit, Replaceable Probe, ±0.01 Ph Accuracy, Lcd Display

Apera Instruments, LLC-AI501 PH700 Benchtop Lab Ph Meter, 0.01 Ph Accuracy, 1-3 Points Auto Calibration, 3-In-1 Ph/Temp. Electrode

APERA INSTRUMENTS AI209 Value Series PH20 Waterproof Ph Tester Kit, ±0.1 Ph Accuracy

APERA INSTRUMENTS AI316 Premium Series PC60 5-In-1 Waterproof Ph/EC (Conductivity) /TDS (Ppm) /Salinity (Ppt) /Temp. Multi-Parameter Pocket Tester Kit

Apera Instruments, LLC-AI481 TN400 Portable Turbidity Meter, Infrared Sensor, ISO 7027 Compliant, EPA Approved Standard Solutions For Easy Calibration