Sorry, I don't see any pictures - the mount is hinged on the starboard side, the port side is rigid. The whole thing has quick releases.
As for why I'm selling it: It doesn't fit my sailing style anymore. I'm transitioning from wild ocean adventures to more of a round the buoys kind of thing. The wind vane worked great - almost like magic, it seemed. We crossed the Med, the Atlantic, Pacific, and even got it working in the Sea of Cortez and its shifty winds.