JBL Water Test with smartphone evaluation for freshwater aquariums, JBL ProScan 25420 (Misc.)
The handling is easy and fun. Values ​​correspond to my droplet test results. The app has a 0,25er scaling for NO2, fine is apparently on a stick not possible. The exact value of 0.1, for example so you get further out with the JBL NO2 Test droplets.