Hoya 37mm Slim Circular Polarizing Filter: Hoya 37mm Slim Circular Polarizing Filter is a lightweight and durable filter that is allow users to remove unwanted reflections from non-metallic surfaces such as water, glass etc. The high-quality optical glass ensures excellent image quality. It enable colours to become more saturated and appear clearer with better contrast. This effect is often used to increase the contrast and saturation in blue skies and white clouds. Hoya's polarising filters do not affect the overall colour balance of a shot.