18 coatings on the lens...well that's a lot of coating and this is just the lower budget K series range to K&F's X and X-pro series which have 24 coating layers. I am reviewing the 67mm Nano K-series here, but I also own the Nano X series of this same ND2-400 filter at 77mm which is about twice the price. So whats the difference? Well having only so far tested this K series filter on a waterfall video scene on my monitor, the only difference is in packaging and presentation. Performance-wise, this filter seems to perform as good as the X series one. As shown in my photos, The filter shows no flare, chromatic aberations, or cross effects. Once I have taken it out for more real world sunny scenes, I will know for sure and update my review. So, in other worlds, this feel as high quality as the more expensive equivalent variable X-series filter. However, when going to approximately 7 stops and over, the colours seemed washed out. Under 7 stops, the colours really pop. At all stops, the picture is sharp in the focus areas. At this point, this feels like terrific value for quality results. Just one grip, I have. There are no intermediate markins for the ND values or stops. Just notches. And there are no clicks, it's all continuous. I would have liked some click stops. But its a very minor grip at this price. One more thing, as shown in my photo, this works and threads smoothy on my K&F step-down rings.