Had trouble posting that don't know why . The little aquarium thermometer is cheap and spot on accurate . Us it to calibrate the accurite the little hygroset II is made for humidors and can be set to the right humidity and of the three I have only one had to be adjusted after calibration .I use them and only them to set my humidity. I have spent lots of money on getting humidity right when I found the hygroset II it was like a godsend .I have a hygrometer that I paid a hundred dollars that doesn't work as good as they do .Got mine off ebay twenty dollars or so each. To calibrate a hygrometer .Use the plastic lid from a gallon milk or water jug fill the lid with table salt and get the salt damp. moist to the touch but not soggy or water standing on top of the salt . Place the hygrometer and the lid in a one gallon ziplock bag . Get the bag as flat as possible and as much air out of it as you can. place the bag in a room as close to 75 degrees as you can . wait 24 hours don't open bag yet but read the humidity . It should be 75 percent . If it isn't make a note of what it is and remember to always figure in that difference when reading your humidity in your incubator . Have a tread you need to read . I'll post a link .