Internal Coating
PRO IRND square and rectangular filters have the ACCUND coating precision bonded to the inside surfaces of the filter stack for maximum protection from scratches. PRO IRND filters can be polished after a scratch to return them to usability. The internal bonding is done specifically for 4x4, 4x5.65, and 6.6x6.6 sizes only due to the environmental factors of matte box use and filter changes.