B+W 55mm XS-Pro HTC Kaesemann Circular Polarizer with Multi-Resistant Nano Coating New generation of Kaesemann High Transmission Circular Polarizer with 1 - 1.5 f-stop loss. Before up to a 3 stop loss. This filter uses our XS-Pro Digital mount which is especially suited for DSLRs with wide angle and zoom lenses. It has a front thread for additional accessories. MRC nano has an improved outer (8th) layer over regular MRC. The nanotechnology based characteristic (lotus effect) produces a better beading effect with water making the cleaning of this filter even simpler and faster than ever before.