Worlds Most Sharp and Color Neutral ND Filter: X4 ND filter has the flattest transmission curve of any ND filter, and performs with unparalleled color neutrality, guaranteed. 

MRC16 Optical Coating: Our state-of-the-art MRC has 16-layers of Multi-Resistant Coating which increases surface resistance while reducing ghosting and lens flare effects. (MRC16) increases light transmission to 99.4% and creates a protective layer that's structurally harder than the glass. MRC16 also helps to reduce reflections to improve the contrast of the image by elimination of stray light. 

Nanotec: Breakthrough's custom nanotec(R) Nano Coating layer repels dirt, water and other elements by beading rather than absorbing, making it easier (and faster) than ever to clean. Nano Coating ensures the surface glass will withstand extreme wind, salt water, dust and other abrasive conditions and elements. Nano coating beads water and other elements rather than absorbing and smearing. 

Sizing: Circular filter thread sizes range from 43-95mm. Square glass is available in 100mm or 150mm sizes. (Lens thread size is typically posted on the front end of lens, otherwise located on the lens barrel. Please be sure to order the correct size, or the filter will not fit directly on your lens) 

25 Year Support: Each filter is guaranteed to be free from defects in materials and workmanship for 25 years from the original date of purchase when used under normal shooting conditions and for the purpose intended. Activation of warranty is required using the filter's assigned serial number, in order to receive warranty benefits. Our guarantee does not apply to accidental damage, unreasonable use or neglect. 

Filter Frames: The ultra-slim double-threaded traction frame permits stacking, and will accept all of your filters and existing lens caps.