So, if you typically put your iPhone on armrests, sofas, or other non-flat surfaces, stop doing that or get a case with
a higher coefficient of friction.
Put differently, the Cold War created
a high coefficient of friction in the global economy.
Not exact matches
They are far lighter and have much
higher friction coefficient and needs a total reworking
of the servo system in order to avoid the horrible lurching stops the first gen systems were known for.