The Danubia 1.5x Erecting Image Prism increases the magnification of the the image by one, whilst also reversing it for easier viewing, as most telescope eypeices, show the image upside down. It is easier to see terrestrial images with a magnifying eyepiece and as it has an erecting image prism, it means that the image being viewed is automatically rotated through 180 degrees so it can be viewed the correct way up.