The Sigma 105mm protective filter is a general-purpose clear protective filter designed to be left on the lens permanently. This filter helps reduce dust, dirt, and moisture that could reach the front lens element of your lens and provides additional protection in case of drops or situations where scratches might occur. - Provides no additional coloration or contrast, allowing you to pair this filter with others - The general protection filter reduces dust, dirt, moisture, and scratches that could reach the front lens element