1. Glass, and Scratch-resistant. 2. Multi-layer coating 3. Aluminum alloy frame, corrosion resistance. 4. 9H hardness,scratch without leaving a mark. Polarizing () Filter: 1. Polarizing filter eliminates reflections from non-metallic surfaces, and increases contrast and color saturation. 2. Removes unwanted reflections from surfaces such as water and glass. ND Filter: 1. Reduce an amount of visible light that enters the lens, allowing the user to utilize apertures or slower shutter speeds, particularly in bright conditions. 2. Work especially well for portraits by allowing the photographer to reduce the depth of field, producing pleasant background while keeping the subject in focus. 3. Emphasize movement by permitting slow shutter speeds in bright light, giving life to photos that would otherwise look freeze in time. 4. This particular filter is multi-coated to minimize reflection on the filter , which reduces flare and ghosting, and produces contrast and well-balanced color. ND filter set weight:about 90g filter weight:about 68g ND 8 16 32 filter:about 83g Colour:As Shown Material:Glass Package Contents: 1 * ND 8 Filter 1 * ND 16 Filter 1 * ND 32 Filter 1 * Filter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.