Double-Threaded for Stacking Filters, B270 Schott Optical Glass, Ultra-Slim Magnalium Rim, 20 Layers of Nano-Coating. The 37mm ND8/ND64/ND1000 Lens Filter Kit Plus+ from Urth includes an ND8 Plus+ ND64 Plus+ and ND1000 Plus+ so you can elevate your landscape photography in different light conditions. By blocking 3 (ND8 Plus+) 6 (ND64 Plus+) or 10 (ND1000 Plus+) f-stops of light the filter kit gives you the creative freedom to explore long exposure and depth of field effects no matter the light conditions. The Plus+ range features 20-layers of nano-coating which provides easier cleaning and better protection against water oil and scratches. These layers also provide a higher maximum light transmission and a more consistent transmission curve for sharper images finer colors and greater depth.