The 1.25" Orion UltraBlock Narrowband telescope eyepiece filter is the filter of choice for deep-sky observers viewing from highly light-polluted sites.
Light pollution can significantly decrease the quality of telescopic views of deep-sky objects. The UltraBlock filter blocks all forms of light pollution from incandescent and fluorescent lighting, including mercury vapor and sodium emission bands, while passing critical hydrogen-beta and ionized oxygen wavelengths. With an UltraBlock telescope eyepiece filter, emission and planetary nebulas "surface" from the washed-out background sky seen from light-polluted areas. With contrast increased, you'll be able to discern more detail in deep-sky observations.
In dark skies, the UltraBlock also enhances the sky presence of a significant number of fainter deep-sky celestial objects. You'll see more of these faint nebulas, galaxies, and clusters with an UltraBlock compared to unfiltered and wideband-filtered views. You'll simply see more with an Orion UltraBlock filter!
The handy 1.25" UltraBlock filter can be installed on any 1.25" filter-threaded Orion telescope eyepiece and many other brands of telescope eyepieces.