Circular Polarizer Screw-In Filter - 25CP – The Tiffen Company
NOVO Excel Pro 58mm Circular Polarizer Filter (Cir-PL)
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Amazon.com : High Definition 52mm CPL Circular Polarizing Filter for Olympus M ED 9-18mm f/4.0-5.6 Micro Four Thirds Lens & Olympus M.ZUIKO Digital ED 12-50mm F3.5-6.3 EZ Lens : Electronics
Why you should always pack a circular polarizer filter in your camera bag – Kevin Lisota Photography