I purchased the StowAway Max in advance of receiving my special ordered Roadtrek, so I haven't actually used it yet. But I found the videos very helpful in assembling it all to the extent I could without a vehicle to mount it on. I noticed the holes for the bolts and washers to mount the rack were drilled near the curved end of the lid, so the washers did not get a good, tight flat fit on the inside of the lid. But, if you tightened them enough, it looks like the rubber washer will keep out moisture. I plan to try to strap down my chair or foldable lounge chair which I used to carry on the ladder rack of my recently sold Chinook. So, I will see if it is secure. Stowaway has great customer service and answers email questions fast.