Haida Circular Polarizing (C-POL) Filters use the neutral polarization material, without any color cast. Through special techniques to glue them together with optical glass, also with special crack resistance treatment. For the concern that you may go to the rain forest where is hot and wet, or to the area where is freezing, so an excellent quality CPL filter must go through the extreme temperature difference. Under these circumstances, an ordinary polarizing filter will always have the problem of air bubble or adhesive failure. But Haida's special strict processing technique just put an end to all these bad results may occur. When using the polarizing filter, smooth rotation will be needed to take the brilliant pictures.Ordinary CPL filters could easily get frozen when in low temperature, or lose the comfortable damping feel in high temperature. Our special processing technique guarantee each CPL filter from Haida has the steady rotating function between -40 and 80.