There's a reason there aren't many around. They didn't work well. A few were sold because that's all that was available at the time. I bought one a few years ago to display with my '38 at shows but ended up selling it because it didn't fit the smaller windows of my car.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.