A quick and easy way to get a look at the charging voltage and battery voltage of the car to throw. Can one also times plugging in colleagues / friends - I think it's practical. The displayed values are okay, agree +/- 0.2 V with the values at a fairly high quality multimeter match, where it reacts faster and thereby probably also results in a certain display difference. As a precision instrument plug is but certainly not to be understood here as a good reference point but already he is good and exactly to my opinion also.