COKIN Wide Angle Filter Holder - P (M) SeriesThis extra thin P (M) Series holder prevents vignetting at wide angle of view. It accepts a filter, which can also be a polarizing filter, for use on super wide-angle lenses (focal lengths less than 20 mm in 35 mm full frame). P-series (M) - recommended for larger thread diameters up to 82 mm and with a clear aperture of 84 mm from 28 mm focal length (based on 35 mm full frame). They are specially designed for today's digital SLR cameras.