This review is for the 2-in-1 True Color ND variable and CPL polarizing filter from K&F Concept's X series (Nano-X).

The advantage of combining dual functions of ND and CPL is the ability to quickly adjust both amount of light and polarization, usually a challenging situation faced outdoors near lakes, pools, or reflecting glass surfaces like high rise windows. The variable ND has 5 stops (ND 32, 16, 8, 4, 2) and rotates infinitely. K&F promises no "X" cross on images. The construction is AGC optical glass with 28 multi-layer plus titanium coating to reduce glare but produce true color with no yellowing.

The 77mm circular filter is lightweight and machined extremely well with an interesting orange tab on each side of the circle for fast adjustments. You grab either tab that is convenient, they both adjust the ND stops.

I was able to easily twist this onto the front of a step-up ring that I have on my Sony alpha 5100.
It's an older camera but the pictures have always been great when using the right combinations of lens and filter. I can confirm that this truly delivers the easiest experience for quickly getting a high quality image by adjusting for light and polarization in one filter.

With the proper assortment of step-up rings, your investment in this filter can pay off by using it on multiple devices you may own. To protect your investment, it comes in a nice faux leather case. This is an outstanding ND + CPL combo for quality images in many outdoor situations and the sliding tab makes adjustment so easy.