I stuck this zaino to need to quickly hold and pose my reflex.

The "K&F Concept 67MM Polarizing Filter Circular Polarizing CPL, Ultra Slim, Japan Optics, Multi-Coated, with Lens Cap" came in a branded box. It was nice to find the filter in a hard plastic case for protection, with a lens cap already attached to the filter. I ordered this filter for a Nikon P900. With the lens cap still attached to the filter, I carefully screwed the thin filter into place. I then took a series of pictures to check its effectiveness, and have included two pictures of the original Nikon lens cap showing the difference. When attempting to remove the filter, I found that it was stuck, so I had to resort to a filter wrench to remove it. The reason it got stuck was because I was turning the polarizing ring clockwise and counterclockwise from my perspective behind the camera. I must have just caught the threaded ring with my finger as I turned it counterclockwise, just enough to lock the filter in place. Some suggestions I have from using the filter; 1. When installing the filter, leave the lens cap on as it gives a larger shooting area. 2. Only turn the filter clockwise when viewing it from behind the camera to avoid repeating my mistake and lock the filter in place. 3. Carry a suitable filter wrench when using one of these filters just in case it gets stuck. 4. If it fits a P900 and it gets stuck. Zoom the lens so it points out about 30mm then remove the battery without turning the camera off. This will stop the lens retracting when the camera is off and if the camera is left on it will stop the lens trying to counteract the movement. 5. The lens and cap are stored in a small cellophane sleeve inside the plastic case. It is best to leave the lens cap on and insert it so that the flap of the cover is on the same side as the lens cap. This virtually eliminates the risk of the sticky flap touching the exposed filter surface. The only thing that would make this filter better is some sort of cover for the exposed surface or attachment points to hold the filter in place inside the case.

I've read bad reviews about people getting the filter stuck or unscrewing during use. If you carefully turn it with the ring in the right direction you won't have any problems I would say. For me these work very well on the Sigma lens.

The filter performs great and produces a good image, I was just a little disappointed with how easily it gets stuck on the lens. I have an nd filter from this same company that is great and is larger around then the front of the lens so it comes off easier. I haven't been able to find a polarizer like that, but if they made one it would be perfect.

Very comfortable with the magnetic mechanism. Several times the screws got stuck in my lenses. With the magnetic ring, they are quick to change and use. The 82mm filters are compatible with the Kase system which offers more filter choices but at a higher price. I now have a mix of both brands and feel great. For a quality price, K&F filters are ideal. I highly recommend them.

The product is okay, but I could hardly see the effect. You also have to be careful not to turn it in too much. Had read in the reviews that it can get stuck and initially had the problem right away. It took me a while to get it off again. Because of the slim factor, you should approach it with caution. Otherwise it can end up expensive.

For the price this is fantastic. I'm only a student so the like of polar pro and such are out of reach and was always stuck with cheap brands (including older K&F's) that ruined image quality with x marks and colour cast.
But then I discovered this and I have to say I'm impressed. No colour casting or 'X' patterns and my footage looks crisp as if there was no filter at all. And the fact that it's a CPL aswell is a huge plus.

Would recommend.

Very comfortable with the magnetic mechanism. The screws got stuck in my lenses several times. With the magnetic ring, they are quick to change and use. For quality money, the K&F filters are in a great place. I highly recommend them