i have used both,both work the same.with the flat one u can keep your window rolled up,its much easier 2 use than the window 1,warmer 2.my current truck has 1 built in,there is a cable jack on the wall just screws in.driving a freightliner m2 bus.class,if you have a laptop comp.with air card u can watch hulu or fancast 2 stay caught up on your favorite shows,u can also go directly 2 abc,nbc etc...just be careful how long u watch ,it really eats up your air card time.