Calibrating my Hygrometer

I know that there are plenty of instructions on how to do this but I just want to make sure I have done it right, sorry if this is another repeat.
I am getting a discrepancy between the Hydra unit read out and my digital hydrometers.
I am going to test my digital hydrometers with a salt test and see which units are out and recalibrate.




Have I done this right?