On the product:
Conductivity meter for measuring water quality and temperature in aquariums, hydroponic and aquaponic systems and drinking water

Measuring water conductivity is very important for hydroponic crops to prepare the irrigation solution. The conductivity meter provides us with information about the amount of solids dissolved in the liquid.
A lower conductivity reading indicates a purer solution.

Device features:

Combined conductivity meter and temperature meter
Has a large and clear digital display
waterproof
Temp measurement in the range of: 0-80 degrees Celsius
Automatic shut-off timer after 5 minutes of inactivity to preserve battery life
Display lock button to save last measurement
TDS: 0-9999ppm
Conductivity: 0-9999us/cm
Runs on a CR2032 battery – supplied with the device