Good product to enter

I bought this product because I am the long-term interest in the field of photography architecture and landscapes.
However, did not want to put right the budget for the Premium ND filter on the table.
The adapter rings are made of metal and are processed dibasic.
The filter holder itself is ok plastic and from a processing perspective.
The filter itself I delivered a practical folding pocket and let be transported as well.

Now for the filters, they are made of plastic and are of the processing team as well ok, as they have no sharp degrees at the edges.

Why then only three points?
Simple answer, they leave an extreme purple color cast in the photo.
This can however be reduced while in the post with the result that the images are to use only in B / W.
Due to the color change these filters are not suitable for high-quality long-term exposures, but allow an inexpensive insight into the long-term photography.