The B+W 55mm Clear Glass XS-Pro Digital Filter features a newly developed mounting ring that is especially suited for SLRs with wide angle & zoom lenses. Its thin profile prevents the mounting ring from vignetting in even the widest shots. The B+W XS-Pro filters have front threads for mounting additional accessories & are made from brass & are matt black to prevent reflections. The B+W Clear Glass XS-PRO Digital Filters are designed to protect the end of your lens without affecting the colour balance of your shot. Its only function is to keep dirt, s&, or splashes away from the front lens. The extremely clear special glass with high transmission is MRC-finished. The Multi-Resistant Coating (MRC) with Nano Technology is an outer layer of protection that comes standard with all XS-PRO Digital MRC filters.