I found an invention on the web which was patented by a guy just this year and can be seen on this site:
http://www.freepatentsonline.com/7036524.pdf
please note: when you pull up this site you'll have to scroll down a bit to find the hyperlink (PDF File) to view the patent including drawings, and specs. Looks like something that should come standard on all RVs.
2006 Montana 3500RL, MorRyde Suspension, W/D, 2nd A/C, Fantastic Fans, MaxxAir, Fireplace, RotoChocks, Slide Awnings. 2005 Ford F350 Lariat LE, PSD 4x4 Dually, Long Bed, C-Betr Mirrors, Vortex Spray-In Liner, Access Tonneau Cover, Remote Starter/Alarm, LED Running Board Lights