The 72mm B+W KSM High Transmission Circular Polarizer is a camera filter designed to reduce reflections and glare while increasing color saturation and contrast. It is made by the brand B+W and has a circular shape with a 72mm filter size. The filter effect is a polarizer, which is useful for outdoor photography and can be rotated to adjust the amount of polarization. The KSM (Kaessmann) mount ensures a secure and precise fit on the lens.