Not waterproof. Bought as BigGulp mug holder, to keep from sliding/tipping from console area floorboard between the two front seats. The unit is very nice, and fit the area with a couple of options. First 40 mile trip I put the mug in the unit. I did not think about it again til I got off the fwy and sitting at a light. I reached down to notice the mug had fallen over completely and was obviously not sealed because about 20 oz of soda had dumped into the unit. Oh, thank goodness it's waterproof! (Or so I thought). Got home and took the unit out to clean it up, and over 1/2 the liquid had soaked thru to the (brand new- excruciatingly expensive floor mats). I was not a happy-camper. But glad it was not worse. And super happy it was not on my seats!! Other than not being waterproof, it is a very nice organizer.