Great quick change ball joint, I'm using it on a mirrorless camera to mount upside down. I was skeptical as the product is outsourced but still quite expensive. But after comparing to other ball joints, it's worth it.
Negative: The safety mechanism of the quick change plate is a bit awkward to open, I don't like it much.
Positive: Outstanding friction control of the ball joint. With released screw the friction is low but not zero, and then tightening the screw, the friction is raising slowly to the highest. Not much effort is needed on the screw handle to achieve full lock on the joint.