Product review (5 stars): Plus or minus variances barely noticeable
Plus or minus variances can be annoying until you understand why they occur. I bought a four-pack, batteries not included, inserted my own of different ages, then put all four in an empty tissue box and covered it. On the way into the box I noted each had already come to a close temperature and the humidity was close, not more than a +/-2 difference. An hour later the temperatures were still very close. Days later the humidity on all four are +/-1 in the 51% range. I have no idea how accurate that is, but they are showing a very similar number in 4 rooms. My rooms have individual in-the-wall electric heaters with a dial and no settings for temperatures, one dimple about 3/4 of the way. I am trying to get a low temp around 68 and that is below the dimple. For me, all four are working perfectly.