Do car vent mounts interfere with vent?

[Irony58]

It's hard to tell from pictures. I'd like to use a vent mount for my phone, but do any (or all) still allow me to change the vent vane angle?

 

[m-cman]

The one I have doesn't allow any changes to the vent louvers. It slips into the opening and catches on the back edges of the louvers. You can slid the mount side to side to change the airflow a little. If you have the heat on it does allow the phone to get hot so if using continuously (like GPS), I turn off the upper vent air flow. Works great when A/C is on though. Keeps phone cool.