So what is the difference between the Ostara Moon & Skyglow filter and the similar priced Crystalview Moon filter ?
The Moon / Skyglow is more of a dual use filter. It cuts down on light reaching the eye, for more comfortable views of the Moon. On top of this, it also helps reduce sodium light (street lights) to aid deep space views. However this does mean you get a bluish tint.
On the other hand, the Ostara CrystalView Moon filter does not act like a light pollution filter . It is more a dedicated Moon filter. For the Lunar observer the advantage of this filter is that it gives a more neutral colour.
So that is the differences between the two filters. If looking for a dual use filter, go for the Moon / Skyglow. Or if you are a dedicated Lunar observer, go for the CrystalView. But there is no harm in having one of each.
Each one comes in its own padded , hard plastic case
Both filters can be purchased from Northern Optics