Paul is the only one that does not use the frame boss as the inside of the pivot axis.
They Make a stainless steel sleeve to go over the frame boss
and then put O rings in to keep the grease clean.
Return coil springs are counterbalanced with a wrench on the flats,
and an allen wrench holding the adjustment ... [and the brake on]
made in California..

My favorite rim brake is Hydraulic.
Magura HS33 fits on V bosses but as an anchor point, not a Pivot.

smooth progressive braking with plenty of power is a Given..
Made in Germany,