Fotodiox shows in the video below how their Polar Throttle adapter works. You can buy the adapter at Amazon US, Amazon DE, Amazon UK, Amazon FR, Amazon IT, Amazon ES.
The youtube video description from Fotodiox:
We’ve all been there. You’re ready to shoot a gorgeous landscape, surging waterfall, or classic car… Suddenly you realize that reflection and haze are reducing detail and contrast, and the image is not as crisp as you know it could be. The solution used to be fumbling around for the right sized circular polarizer for your lens, but now with the new Polar Throttle, you can just dial in the CPL filter that’s built right into the lens adapter itself!
