The Danubia Erecting Image Eyepiece 6-18mm Zoom 1 Inch, reverses the image in the telescope for easy viewing, so is perfect when spending long periods star gazing. It will also help when using sky maps, as it is quicker to work out what is being seen.. Useful for both Danubia by Dorr reflector and refractor telescopes, the Eyepiece is really easy to fix..