Do the OSMO Universal Mount and Straight Extension Arm have friction swivels like the beautifully engineered phone mount, or are they locked in one position?

I'm thinking specifically in terms of flipping an external microphone to face forwards or backwards, while also monitoring on my phone.

The Osmo Universal Mount and Straight Extension Arm are not designed to rotate freely while using. Well, you can mount them to the rosette mount of Osmo in any solid direction. For the details, please refer to the guide introduction in DJI official website: http://www.dji.com/product/osmo/info#downloads