What type of hygrometers is everyone using to determine humidity in the safe?

Is one of those simple ones from petco adequate?

https://www.petco.com/shop/en/petcostore/product/imagitarium-round-humidity-gauge-2388571?cm_mmc=PSH-_-GGL-_-CAL-_-PME-_-PET-_-AQU-_-0-_-PM_GGL_FY20_SBU05_SH13_SmallAnimalBird&ReptileSupplies_ReptileAccessories_PLA-SMRT-_-Product_Listing_Ads-_-Smart_Shopping&ReptileSupplies_ReptileAccessories_PLA-SMRT-_-Product_Listing_Ads-_-Smart_Shopping&kpid=go_9411562751_95036224949_419469053952_pla-890249194709_c&utm_config=tad0iunwp&utm_campaign=PM_GGL_FY20_SBU05_SH13_SmallAnimalBird&ReptileSupplies_ReptileAccessories_PLA-SMRT&ReptileSupplies_ReptileAccessories_PLA-SMRT&utm_source=google&gclid=Cj0KCQjw-_j1BRDkARIsAJcfmTGyYDrw-Er1fD7Zuor2QMQ2gx5nlEizH7mDF_IuRJi35IrFKLBwocIaArHeEALw_wcB

On the cheap hygrometers, you never know how accurate they are. What I do is when I'm looking for one,
is look at all of them in the store and pick the one from the group that reads closest to the same.
Still not scientific, but hey, you just can't have it all.
Dennis

I have a cheap hydrometer that I originally got for my guitar case.  I compare the readings I have in the safe with a similar hydrometer I use to monitor the bedroom temp and humidity.  Accuracy is good enough for me.

I have a few bluetooth (GOVee) and WiFi (Shelly cloud) ones.  They're accurate enough.