I have the Spigen magnetic air vent with the carbon fiber look to it. it's more of a hexagon shape than circular. the magnets are strong on it but I've learned that when pulling the phone off, you need to pull to one side towards the opposite side so that way you don't pull out the actual holder from the vents. it's kinda like the motion you use when using a bottle opener. Ever since I've switched to that motion for removing the phone i've had no problems.