Heliopan 77mm Circular Polarizer SH-PMC Filter (707746) with specialty Schott glass in floating brass ring Removes Reflections And Increases Color Saturation Without Affecting The Overall Color Balance 16-Layer Multi-Coating Filter Factor: Between 2.3 And 2.8 (Approx. +1.3 Stops) For brilliant color reproduction, best contrast and sharpness Heliopan offers the highest quality optical glass from the German Schott Group. SH-PMC broadband coatings of 8 layers per side for the highest reflection reduction (below 0.2%). Dust and moisture repellent top coating on each side for easy cleaning and longest life Minimal reflections because of matte black anodized brass filter rims which will not bind when threaded in combination with other metals. Limited Lifetime Warranty