After eyepieces, zenith prisms are the most important accessories for refractors and Schmidt-Cassegrain or Maksutov reflector telescopes. They are required for a more comfortable view during zenith observations or for image reversal.
For optical reasons, these accessories cannot be used on Newtonian reflectors - and do not need to be, as the beam path in the Newtonian telescope makes this unnecessary. This zenith prism provides an upright, inverted image. All Celestron zenith prisms have a high-quality coating.