Accurate hygrometer

I have a bunch of different ones including the ac infinity sensor one. They all read differently all the time. Does a truly accurate hygrometer exist? And where do you get them? Or do you just pick the one you like best and decide that it is accurate above all others and just go with it?

Check out rh% meter salt calibration.

It's easy to check/test them.

I have about 10 of the small hygrometers for my curing jars and I salt test all of them so I know how far off they are. If they read 77 for example, I know I have deduct 2 degrees and if they read 73 I know I have to add 2 degrees to be accurate. Simple.

I store all my humidity gauges in a heavy duty freezer ziploc bag with Boveda 62% RH. packet's. The gauges i use, i can adjust while still in the bag before i take them out, if they are off any.