New aerodynamics?

Looks more like a rub guard to me than anything to do with aerodynamics

 

I would think it should go from the top to the bottom to be more effective.

 

They make CARB happy, with minimum cost and up keep.

 

Yep those deflectors are registered with CARB and when combined with low rolling resistance tires makes your trailer CARB compliant.....

They cost about a grand as a Kit (there should also be a piece on top). About the same as skirts and tend to have/cause less problems. Pretty sure they weigh less than skirts.

For me they were the most cost effective way to get compliant. I mostly run the west coast so rarely run fast enough for any Aero stuff to work.

 

Not a bit......

I do need to trim the top piece so that it does not interfere with the latches