The B+W 77mm Skylight KR-1.5 (1A) Filter is a general use filter with a slight pink tint to help improve overall color accuracy and clarity. The light pink coloration helps to reduce the overall bluish cast of daylight and is especially effective when photographing landscapes and in shade. The Sky 1A filter is also useful as a general protective filter to leave on lenses at all times. Filters help to reduce dust and moisture from reaching your lens element and provide additional protection in case of drops or situations where scratching could occur. B+W filters are constructed from high quality Schott glass for increased optical clarity and color fidelity. They feature a brass filter ring for durability as well as jamming prevention.