This was the combination of two high quality filters - Grey Filter and Polarizing Filter. On the one hand, the neutral grey colour reduces the amount of light entering by 10 aperture levels. Wherever necessary or for a special image effect, you can work with longer closing times. On the other hand, the polarisation effect prevents unwanted reflections and gives picture results an exciting, richer colour dynamic. Characteristic of PolarPro Quartzline filters is their perfect colour neutral. Where picture results with other filters may tend to magenta or green, although only slightly, Quartzline filters produce practically no deviation from the real subject colours. These filters are your guarantee for true-to-life colours! PolarPro Quartzline series filters are made of 99.9% pure quartz glass, which ensures unparalleled durability and clarity. The glass has a very low refractive index of only 1.46, so that no loss of sharpness occurs when using this filter. In addition, quartz glass is also extremely temperature-resistant and is ideal for sensors up to 100 megapixels. Perfect for photographers and filmmakers who like to work in extreme conditions! Each quartz filter glass is coated with 16 ultra-thin layers. The various coatings ensure optimal scratches, water and grease resistance, avoid reflections and a strong reduction in the risk of vignetting. In addition, they ensure a very high light transmission and a hyperneutral colour reproduction. A well-known problem with many filters is that when screwed into the lens thread, they are concealed unless they are exactly attached. Particularly aluminium or even plastic sockets are quickly damaged. The PolarPro Quartzline filter holders are therefore made of robust brass. This high-quality metal makes screwing and unscrewing much easier. And by the way, this gold-coloured filter holder also looks luxurious and aesthetic.