If you are newer to all this and want to use a hygrometer that's cool, I'm about 6 months in and weening myself off checking it. I would suggest a digital model, you can grab them on amazon for 15 bucks or so. I got 2
Caliber III Thermometer Hygrometer by Western Humidor, they were like 10 bucks each. One for each box, if you have a winadoor you can put one in it at the top, then when you want you can move it to the bottom, haha. Don't really need two one would do it.
