The Alpha II circular polarizer, now updated with a thinner frame and improved glass, is a great entry-level filter for those starting out their photography education. Providing the same level of polarization as other filters. Circular polarizing filters give scenic photography more punch by darkening blue skies so that white clouds and foliage stand out. Light rays become polarized when traveling through moisture and pollution in the atmosphere as well as when they reflect off non-metallic surfaces. A polarizing filter absorbs polarized light and helps remove unwanted reflections from non-metallic surfaces such as glass or water. By removing these reflections, this filter also increases color saturation, especially in leaves and foliage. Improved Glass from Alpha I Thinner frame design Rotating frame construction Filter at a Glance Filter Factor: 2 stops Glass Type: Hoya Standard Light Transmission: N/A Number of Multi-Coatings: Zero Nano-Coating Technology No Hardened Top Layer: No Anti-Static No Black Rimmed Glass No Frame Construction Standard Profile / Aluminum Front Filter Threads Yes