This product has been opened for inspection, but it is new and unused. The outer box has some minor stains. Please check the images. Model Number: Canon Drop-In Circular Polarizing Filter PL-C52 for Cameras Compatible Models: EF300mm F2.8L IS II USM, EF400mm F4 DO IS II USM, EF400mm F2.8L IS II USM, EF500mm F4L IS II USM, EF600mm F4L IS II USM, EF200-400mm F4L IS USM Extender 1.4x Description: A drop-in type circular polarizing filter. This polarizing filter controls harmful reflections that interfere with the subject's depiction, enhancing the shooting effect. It can be used to remove reflections from glass surfaces and water surfaces, or to emphasize the blueness of the sky. The filter can be rotated even when attached. 01