A Circular Polarizer is the must have filter for every photographer and Hoya's Nxt Plus is a powerful upgrade to the best-selling Nxt series. The new filter employs a waterproof top-coat to Hoya's polished smooth ""Clear"" glass for easy cleaning. Dirt, smudges and water wipe away easily. Using 10 layers of Hoya's patented anti-reflection (Ar) multi-coatings your images show improved contrast, color and sharpness. The polarizing film is optical thin with a filter factor of 1.72 for faster Af and improved viewing over standard Pl films. Hoya's high quality polarized glass is mounted into a precision milled aluminum slim frame, making it lightweight and perfect for your wide-angle lenses. Despite the slim profile the filter includes front filter threads so you can attach additional filters or your protective lens cap. What does a Polarizer do Polarizers do one thing: Remove Reflections. Think sunglasses for your lenses. By removing reflections, you reveal the color, texture and detail beneath. So, leaves are greener, skies are bluer and the beautiful rocks at the bottom of that secret mountain lake are revealed. Crpl's are also great for removing reflections from car windows, painted surfaces or just about any non-metallic surface. Depending on the lighting conditions the effect can be dramatic or subtle but it never hurts to pop it on and give it a try. Circular polarizers are easy to use too. Once attached to your lens simply rotate the outer ring of the filter while looking through your viewfinder or Lcd screen until you achieve the right amount of reflection control. When the colors and detail look right, take the picture..