This is some simple screw caps for covering 10 mm mounting holes (counterbores for mounting with screws). They're 10 mm with small flanges for extra grip into the holes.
There is also a model for a simple round standoff, used to get the sign to protrude slightly from the wall.
If you want to see more about the sign: https://youtu.be/Q3_qtvtUXcE
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