Vivitar cromo blend filters

I posted a similar query last year unsuccessfully on another forum somewhere,
and apologise if I'm duplicating it anywhere here.

Anyway...I've seen more of these filters on Ebay, and it seems they have to be used with a polarising filter....can anyone explain how it all works, and what the results are likely to be. Thanks

Don't know why it works. But depending on the filter it will change color as you rotate the polarizer. I've got one floating around here that I got with a camera package of some sort. There were three or four different color combinations available.