Well like everyone else says, this product is ok for temperature but leaves a lot to be desired for reading humidity. This being said, with a few mods it works fine as a hygrometer. I added a few more holes with a drill approx 1/8" and now it actually reads humidity quite well. I added a total of 13 holes around the unit, 5 on each side and 3 on the bottom. Now it adjusts the humidity reading every 15-20 seconds and levels out in about 10 minutes and actually reads the right humidity when compared to my dial hygrometer. So this tells me that there is a design flaw with the amount of air flow allowed by the factory vents, thus not allowing the unit to process the volume of air needed to make accurate readings.

These fit my 2013 Ram perfect.. Exceeded my expectation and quality seems like it will last for decades. Very impressed!