You can buy it from here: https://electronics.semaf.at/INA3221-3-Kanal-i2c-Spannung-Strom-Sensor-26V-32A-max
SwitchDoc Labs, LLC September 2019 - updated to Python 3
Run testINA3221.py to test all three channels
More Information on https://www.switchdoc.com/2015/03/sunairplus-solar-power-ina3221-python-raspberry-pi-library-released/