Since I at windscreen suction cups always have fear that I suddenly smartphone flies through the car with any major temperature fluctuation, this time I opted for the experiment air vent mount - and at least for this model I can say that experiment failed.
Problem: You see after final assembly, as the holder is actually located and how usable the mobile phone is so. It then notes that the situation is not ideal, the real drama begins: to remove the bracket requires a sufficient portion of fine motor skills, tools and lots of luck.
The result is with me fortunately no major scratches on the grating or other damage, except that one of the small springs of the fixture now resides inside my vent and hopefully havoc there in the course of their existence no harm.
Material and presentation of the holder, I consider the price and the description appropriate, but the underlying principle is useless in my eyes.
Conclusion: spring disappeared in the vehicle, the rest of the bracket in the trash.