I have worked with K&F Concept filters in the past and generally had good experiences with them. They're good, mid-range quality filters at (usually) a budget price. I haven't worked with any black diffusion filters prior to this one so I have no basis against which to compare, but so far it seems to work as designed and seems to be made very well.

In a nutshell, this type of filter softens light a bit, causing some gentle halos around light sources, without impacting image sharpness or detail. Where I have seen the most noticeable impact is in images where there otherwise would be a lot of shadows and contrast; instead of stark contrast and strong shadows, the filter has the effect of brightening up the shadows somewhat and creating smoother color gradients. Sure, this can be done in software after the fact, but it is a lot easier to do this at the time the image is taken and it certainly is a lot less work.

The filter is very easy to install. This is my first magnetic filter and it is as easy to attach to my camera as I could have hoped. The threaded ring attaches to the lens in the same manner as a step ring or another filter, and the filter itself just snaps securely into place due to the magnetics. Removing the filter is just as simple, especially if you choose to leave the magnetic ring in place on the lens.

The assembly seems to be well made. I have had filters in the past that have been poorly constructed and rattle in the frames when shaken, or have been mildly blemished, or just felt cheap. This filter has none of those issues and appears to be well made.

This is a nice black diffusion filter. It's easy to install and use, and it just works. I will be using it more in the coming weeks.