by Sam. » Fri Oct 23, 2020 6:35 am
Image A measures specific gravity, you need to take a measurement at the start and end of fermentation and the difference helps you calculate alcohol percentage produced.
Image B measures alcohol content of distillate, ie after it had been through the still. Useless in the wash.
Might need to do some reading through the newbies section here and be careful of misinformation on you tube