Since the item is from China, there is some quality issue ,the first piece that I received didn't have any Polarisation effect . No blue sky and even on testing the item with polaroid test card (provided by my sunglass) had no results.
The second piece works like a charm. I am getting blue sky and very much happy with the product. So do try more than one sample if you find CPL is not working.
Thanks Amazon for bringing such a nice product at right price . Pictures are taken with NIKON D5100, NIKKOR Lens 28-300MM F/3.5-5.6 , Settings 50 mm, 1/200 Sec at F/16, ISO 450.