I'm not a professional, I only have two decent SLR cameras with decent lenses, and I mostly photograph landscapes and animals on vacation. Unfortunately, I use this equipment far too rarely in my free time...but I think I can give a useful assessment of this filter here.

I've been using K&F filters for years and am consistently satisfied with the quality.

This concept of an adjustable neutral density filter, however, is completely new to me.

So far, I've only used neutral density filters as static filters with values ​​of 4 and 8. I'm generally comfortable with them and can achieve the desired effects and results. For example, I can darken snowy beaches completely bathed in sunlight to a level that's easy for the camera to handle, or enable longer exposure times in light/shadow landscapes. You can also achieve good effects with flowing water with it...but every ambitious photographer knows that.

This adjustable neutral density filter actually works like a polarizing filter. It slides very smoothly, and the integrated grip distinguishes it positively from my polarizing filters.
The 77mm thread is very precisely machined. Inserting it into the lens is absolutely no problem.

With the filter attached, it might no longer be possible to use the lens hood. It would even still work for me...but inserting the filter and operating it is a bit cumbersome. So I simply leave the lens hood off...

The filter is completely color-neutral. This can easily be verified with a few test shots. The adjustability is truly fluid, meaning it's stepless.

I'll probably never need the maximum setting of 32...but as I said, I'm not a professional.

Unfortunately, the weather right now isn't ideal for a comprehensive test. So I can't upload any meaningful sample images. I'll be happy to provide them later...

First pictures in the forest with light and shadow, or pictures of the (unfortunately gray) sky on house facades and trees, are promising.

The filter comes with a decent case and is reliably protected inside.

My conclusion: a useful addition to my equipment. How often and for what purposes I'll actually use it remains to be seen. I'm off to Cyprus soon...let's see what it can do there...

Pictures to follow...