High-quality optical glass is developed to meet the performance needs of Zeiss lenses. The proven T*coating minimizes light reflections on glass-air surfaces and improves transmission. In addition to the filter function, the front lens element is protected against contamination and scratches. With the standard thread diameter of 49mm, the filter also fits the lenses of other manufacturers. Model # 2003-603 Features: Carl Zeiss filters are perfectly matched to Zeiss lenses A robust filter mount ensures maximum mechanical quality High fit accuracy guarantees uncomplicated filter change.