As regards keeping your car dry yes they do! The best place to get them is where they are made in Salford at the factory! I have one and used it for 6 plus years when my car was in a barn 1995 to 2002 and it worked very well! I can talk to you about them if you want! I have attached a pic of my one when I was using it over Christmas 2009 as I had to put my toy outside when it snowed!

They really are a superb bit of kit!