We have been testing this item and I just love it! If you care enough to cover your car, you obviously don't want moisture inside the car. The moisture can come from water under the car, wet carpet from driving on a rainy or snowy day, or just from the overnight dew if the windows were open, etc. This great little product absorbs the moisture and when it gets full, the button turns pink to let you know. Just microwave it for 6 minutes or so and all the water is gone again. You can just keep re-using this item over and over again. Check it out, they give great peace of mind knowing the inside of you car is staying dry!