It's improved supression of chromatic aberrations for astrophotography applications
The high quality of filters permits stacking with no image degradation
Without any contrast enhancement, and give a very good idea of the planetary contrast improvement that is seen visually
Neutral density filters are excellent filters to reduce the overall brightness of an image to cut down glare while viewing bright astronomical objects through a telescope
These three ND moon filters are useful for splitting binary systems; comfortably observing the moon; or stacking with other planetary filters