With the Hoya UX Polarization Filter II 40.5mm, you can prevent reflection of water, glasses, or windows of buildings on your photos. that way, you can take photos of landscapes where you see the bottom of the lake instead of the reflection of the sky. This polarization filter guides the light, so the light fall on the sensor from 1 direction. That provides more contrast in your photos. That way, you can use the filter to take photos of cloudy skies. The filter is easy to use. Screw the filter onto your lens, and filter the reflection by turning the front element. Thanks to the thin design of the filter, you won't have dark edges on your photos if you use a wide-angle lens.