The Matte Box is easy to mount on the front of a lens using the various adapter rings. Two slots for 4” x 5.65” filters are included. This allows you to combine an ND filter with a Black Mist filter, for example. The respective adapter rings also have a filter thread, so that, for example, a 67mm filter could also be attached to the 67mm adapter ring.
It is relatively easy to use. In some cases, the matte box could feel a bit more valuable. However, the fact that it consists largely of plastic is beneficial, at least in terms of its low weight. There are threads on the bottom, back and top, which can also be used to attach the Matte Box or connect other accessories. There is also a hot shoe on the top, but the top flag tends to get in the way.
I like how compact and lightweight the Matte Box is, the functionality is good.
I find it negative how big the storage and transport bag is. It is a large hard-shell box and there is a very spacious recess for the adapter rings, which makes the height greater than if you had only designed the bag for the matte box. I find it a bit cumbersome in the form, but otherwise it's nice that one is included at all, which is why I don't give a deduction for it here.
Overall, I am very satisfied with the K&F Concept Matte Box. It is a good alternative to existing brands in this area.