This is a sensitivity check Tube for confirming the normal operation of Handy Water Meter "AQUAB" series.
There are two types available: one for model AQ-201/AQ-201P and another for model AQ-202/AQ-202P (identified by the color of the color marker).

Main Specifications for AQ-201/AQ-201P:

Standard concentration: 1.35–1.65 mg/L
Reproducibility: ±0.01 mg/L
Color marker: Red

Functions of the Check Tube:

1. Confirming Normal Measurement Results
Checks whether the same unit consistently shows measurement values within the "standard concentration" range.

2. Confirming Reproducibility of Repeated Measurements
By pressing the measurement button several times to repeat the measurement, it checks whether the measurement results stay within the "reproducibility" standard.

After use, attach the included protective cap, store it in an aluminum bag, and avoid places with high temperature and humidity.