OSMO Action Filter (Professional) The OSMO Action Filters(Professional) uses German SCHOTT glass as its base material, utilizing multiple grinding and polishing processes. A nanometer-scale, double-sided, multi-layer vacuum coating process ensures a first-class waterproof, oil-proof, dust-proof, and anti-scratch protection. Directly attach the filter to ensure its anti-water and anti-dust capacity, which can be damaged during replacement. Made of aeronautic aluminum, the frame features a knurling pattern to ensure quick attachment. The inside part of the frame is covered with silica gel to protect the original filter from being scratched during attachment.