Robert the side-to-side louver movement is very good - from "in your face" wind to side glass no problem!

Up and down are limited but I found the coverage to be good in the neutral position - the place where the vents want to be with the holders in place. This is a compromise but small payment for having some real cup holders in an MBZ!

Don't be afraid to install them and experiment - you can remove them easily enough and they don't mar the vents in any way I can see.

Mike