Orion 5657 2-Inch UltraBlock Narrowband Eyepiece Filter The Orion UltraBlock is the ideal eyepiece filter for deep-sky observers located at highly light-polluted sites Narrowband filter blocks all forms of light pollution Enhances the presence of a significant number of fainter deep-sky objects Compatible with threaded Orion 2" eyepieces. Metal filter cell construction. Save yourself a trip to dark skies - with the UltraBlock filter you can enjoy the stars from the suburbs!