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I'm not sure I understand how this works. Can someone explain?

When you glue the bearing to a surface, the knob/wheel turns freely.

Under the nob there is a fake finger, which is always touching the touch-screen.

So when you turn the knob, the touch screen registers a "finger" going around in circles.

Givent hat there already is a large touchscreen, this is much simpler than cutting a hole in the screen and fitting a traditional knob.

I'm assuming the screen is capacitive in that car which would allow the fake finger to hover without even touching the screen. Less wear/friction that way.

I wonder. It would be neat to see a teardown. I am also interested in how this holds up over time. I am sure they tested it a ton to make sure it is durable, but what happens if a kid grabs it and pulls it down or away from the screen? I have faith the epoxy they use is incredible strong, but then what happens to the screen? What will it do to that? It could be that it is as durable as any other in-car volume knob, but the damage would be worse as the whole touchscreen would likely need to be replaced.

Or, more likely, you touching the knob adds the capacitance needed to complete the signal.

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