I bought a westernhumidor Caliber lll for $25 @ my local b&m and the instructions say DO NOT do a "salt test" on these units ! So, Im just going to trust it. I did use it to "calibrate" my analog hygrometer but notice that the analog one always reads something other than what the digital reads...no matter how many times i adjust it to the digital, which drove me crazy the 1st few times I reset it. Now I just figured it's not worth it. They are too unreliable to use but, they do look great in the spot made for them in my humidor. I know they sell "better" analog units but, these are not the ones included with most humidors sold today.