Trijicon Optic Cover, Fits Trijicon MRO, Clear Lens, Black Finish AC31021 Protect the MRO lenses, and keep them clear of rain, snow, mud or other debris. The MRO cover has integral lens covers and a protective armor body that can't fall off or get lost. Low profile design allows covers to be quickly operated with one hand. Covers nest together so they don't flop under recoil. Receptive to most spray paints and hydro dip process.