The UV blocking filter blocks ultraviolet light and thereby prevents aberrations eg blue tint or blur. Particularly useful with reinforced occurring UV light as in the mountains or at the seaside.The color-neutral optical glass is extremely Transparent (98%), on both sides of multilayer hardened and tempered Extremely hard (grade 9). The UV filter not only ensures better image quality, but also protects the front lens against scratches and impact damage, water, dust and dirt.The holder is made of matt black anodized aircraft aluminum. The ultra slim design of only 3mm allows the use of wide-angle lenses to a minimum focal length of 17mm with full-frame 10mm or APS-C sensor cameras.Despite the extremely flat design of the filter also has a front thread, so the further filter, a lens hood or Snap-on cover can be attached.The respective filter size is printed in white on the edge.