K&F’s Clip-on Circular Polarising Filter works just fine with the 3-camera array on my iPhone pro max. It’s easy to mount and remove from the phone when needed. There are rubber pads to protect your phone from the plastic of the clip that holds it in place. It comes with a nice microfibre cloth for cleaning it, inside a plastic clamshell case. (You can store the filter and the cloth in the case.

The filter does a good job with my iPhone; it makes the sky a deeper blue and removes glare from water. It makes the image a little darker; but it isn’t an ND filter for shooting in bright light. I It also made my monitor go completely black when I pointed it at it. The clip makes the filter work with I assume most phones, it does block a bit of your screen in use so you may need to consider where camera controls are when using it. When not using it, I just clipped it to the strap on my backpack.

It didn’t make any appreciable difference to the quality of photos taken with it – outside of the improvement in the look of sky and reflective glare. It also worked shooting through windows removing a lot of the reflections.