Sigma 52mm WR Circular Polarising Filter

Sigma's weather-resistant (WR) circular polariser (CP) filters remove reflections on the water's surface and glass windows, and increases the contrast in landscape photography. This effect is often used to increase the contrast and saturation in blue skies and white clouds. With excellent water and oil repellent functions, the filter surface repels water drops and provides resistance to fingerprints.

Even if they appear on the surface they can be easily removed.