Neutral density + polarization filters, or ND/PL filters for short, are a unique type of camera filter that combines two popular filter effects together into a single glass element. ND/PL filters combine a polarized glass element with a neutral density coating of a specified strength for slowing shutter speeds with improved contrast and color saturation.  FEATURES Cinema Series™ Glass - Made in Germany. Brass Frame - Smooth threading and increased durability. Perfect Color Neutrality - Our coating process produces zero color shift. 16 Coating Layers - Anti-scratch / anti-oil / hydrophobic coatings. Adventure Assurance™ - Be satisfied with your PolarPro gear throughout your adventures or your money back.