Gravity is what holds this. Can slip.a.little of pho E on a cover bit actually better than I would have thought in terms of holding the phone.
Pros: we say to install and remove. Holds the phone sturdily 99% of the time. Cons: can't use it on portrait mode (horizontally) and takes the vent mostly out of action as a vent. Eg air flow.di.inishes 90%