Bernard:
The filter is taped to the front of a Cokin X-Pro holder and then slipped over the lens until the front of the lens hood touches the filter. On the Mamiya 28mm I made a foam donut that I attached inside the back of the filter holder (instead of using the universal mount), and that fits over the lens hood by friction - then I could rotate it as needed. With the Nikon I just layered some strips of velcro around the back of the lens hood and on the inside of the filter holder. What I found was that no matter what the light direction, the polarizer was most effective when it was straight up and down on the holder - no rotation needed. That is a good thing since you do get dark corners with the filter on a fullframe Nikon when you rotate it - but none when the filter is used straight up an down. It is an expensive, sloppy, and bulky system but does work on a fullframe Nikon or with the Mamiya and a P-45+.