Fine planetary detail is almost always enhanced with the use of color filters. Since different planets exhibit different colors on their surfaces, it only makes sense that if a filter restricts a neutral color and transmits a feature color
This long-pass filter limits transmission of light with wavelengths longer than 650nm. Whilst suppressing all other polluting lights, the filter allows you to observe emission nebulae with greatly enhanced contrast.
A unique filter for many different astronomical tasks. Incomparable in accracy to combinations of generic color filters made of raw polished glass Ė where surface inaccuracy adds up in the optical wave front to an unbearable degree!