Originally Posted by Bob Denman
The 660 was never meant for use in an RV (I know: I had one on my Spyder...)
The 770 will allow you to tailor your route so that you avoid places where your rig will get squished...
However: the 660 is waterproof, so you can take it in the shower with you!
You must be talking about a different 660. I would definitely NOT take it into the shower: