Radian Triad Ultra Narrowband Filter

I purchased this a few months back when I got my UltraCat, but I have since switched to the broader band Antlia Quad Band filter.  It is in excellent condition with the manufacturers original packaging.

From the Optcorp/radian website:

Unmatched Multi-Narrowband Performance

The Triad Ultra filter stands alone in its class as a filter with four ultra-narrow bandpasses that cover Hydrogen alpha, Hydrogen beta, Sulfur II, and Oxygen III wavelengths - the four most common wavelengths for narrowband astrophotography. As a multi-narrowband filter, the Triad Ultra is designed to photograph emission nebulae, planetary nebulae, and supernova remnants, and excels at doing so from light pollution. However, we recommend you try it from dark skies as well - the narrow bandpasses will give you tighter stars and more pronounced nebulosity.

  Hydrogen-beta Oxygen III Hydrogen-alpha Sulfur II FWHM 5nm 4nm 4nm 4nm Peak Transmission 79% 97% 87% 90%