great accessory for the avid photographer filter allows you to decide which types of reflected light enter your camera lens remove unwanted reflections from water, glass, etc. great accessory for the avid photographer filter allows you to decide which types of reflected light enter your camera lens remove unwanted reflections from water, glass, etc. polarizer saturates colors and increases contrast circular polarizer designed for today's newer split-beam metering systems uses in auto-focus cameras mount rotates to control effect creates dramatic sky/cloud contrast 55mm diameter parallel imported warranty: warranty one year delivery within 2-4 business days