The Hoya 46 mm C2 Blue Cooling Color Correction Multi-Coated Glass Filter is a precise optical accessory for photographers who require accurate color temperature adjustment. This filter provides a cooling effect of 200 Kelvin with a Mired shift of -20, effectively compensating for warm light sources to achieve correct white balance. Made from high-quality optical glass with advanced multi-coating technology (HMC), it significantly reduces reflections, lens flares, and ghosting while maintaining over 97 percent light transmission for optimal image sharpness and brightness. The 46 mm thread size ensures compatibility with corresponding lens diameters. This filter is particularly useful when working with tungsten-balanced film under warm lighting conditions such as candlelight or low-voltage incandescent bulbs, as well as in golden hour photography with daylight-balanced film to neutralize excessive warmth. The multi-layer coating enhances performance with modern multi-coated lenses and preserves optical quality while providing even color correction. Its durable construction and precise craftsmanship make it suitable for professional and aspiring photographers seeking reliable color temperature control in various shooting situations. Its neutral density properties ensure minimal impact on exposure settings while delivering the intended cooling effect for accurate color reproduction in challenging lighting environments.