For the accessories I've used, it's been the texture of the materials providing most of the static friction, leather/rubber both have high static friction combi

For the accessories I've used, it's been the texture of the materials providing most of the static friction, leather/rubber both have high static friction combined with the amount of force pressing them to the back glass. I have a magsafe car mount, and I'm pretty sure I could get in a car accident without it moving, but with a fairly simple twist I can pull it right off.