I received the graduated filter today and tested it right away. The quality is great and I was able to install it in my Puk filter with the existing 67mm internal thread on the outside. This is, of course, another nice extra and saves space for all the packaging in your backpack. Speaking of packaging, the filter is delivered in plastic packaging with a foam pad and was firmly in my place. BUT there was a fingerprint on it! But that could easily be removed with a glasses cleaning cloth.

Before spending € 150 on a rectangular filter set, you should definitely have tested this € 20 alternative. The graduated filter leaves (at the right angle to the sun -> 90 ° or more) a beautiful color value (see photo) and reduces the burning out of the sky many times over. If the blue value is too intense for you, you can of course also play with the exposure time / ISO to set the whole thing perfectly for you. Before buying, you should of course make sure that you use the lens diameter of your largest lens (in your collection) as a guide and compensate for this with adapter rings. The filter also worked without problems with my Tele (Tamron AF SP 70-300mm 4-5.6 Di VC USD). With wide angle, however, I have nothing to say. I think as long as you are under 12mm focal length, everything should be great.

+ easy
+ good price / performance ratio
+ Packaging
+ Coloring
+ variably adjustable
+ Internal thread (additional filters can be attached)

- the only disadvantage in my opinion to a rectangular filter is that you cannot adjust the gradient vertically.

I hope I could help a little.

Good quality filter, built with German SCHOTT glass and installed in a strong and light metal ring.

The ND filter - Neutral Density - by K&F concept is built with an excellent German glass to which a multi-layer NANO coating has been applied (18 layers according to the manufacturer) which allow a light transmittance of 12.5% ​​and a reflectivity of 1.5%.
The glass also has an anti-scratch and waterproof coating which makes it ideal even in precarious weather situations.

The neutral density tint is well applied to the filter and has a smooth, well-balanced transition.

The outer ring is machined on numerical control machines. The feeling of grip is high and the rotation of the ring fluid; the latter is especially convenient during the positioning of the filter during shooting.

The neutrality in the filter is high and the images taken, even at long exposure, do not have color casts.

I bought the 58mm diameter version but there are various sizes on the market to adapt to your lenses.

The cost of the filter is € 39.99 in May 2021. Maybe a little high for the diameter in my possession but the quality of the glass is good.

I insert photos of the product. I hope my review will be useful for a possible future purchase. See you next review!