From Manufacturer
Made to fit most 1.25" eyepieces and accessories, Celestron specifically designed their Mars Observing Eyepiece Filter to selectively pass the ideal wavelengths for viewing the red planet. By combining the best properties of red and blue planetary filters, users will be able to view the polar ice caps and meridian details that used to require two different filters and the need to switch them out. Using this filter reduces glare and light-scattering while improving contrast, definition, and resolution. Engineered for durability and a long life, the filter is made of multi-coated glass with an anodized aluminum frame.