The B+W 39mm XS-Pro Clear MRC-Nano 007 Filter is a simple, clear filter with a 1x filter factor and is designed to provide general protection for your lens. This optically clear filter does not affect overall image quality while helping to reduce dust, scratches, moisture, and other elements from damaging your lens. To prevent internal ghosting and reflections while providing over 99.8% light transmission, each glass surface includes multiple layers of anti-reflection coating. This Multi-Resistant Coating (MRC) also offers greater protection to the filter substrate and helps it to stay clean for longer than with uncoated filters. The Nano coating associated with XS-Pro filters provides an additional eighth layer over the MRC, resulting in an improved beading effect when in contact with water for greater cleaning efficiency.