A high quality 45° erecting prism that screws directly on the back thread of Meade ETX telescopes as well as the popular 4 SE. This provides a comfortable angle and correct image for terrestrial observing.
A Star Diagonal brings the eyepiece out at 90 degrees from the telescope tube, allowing comfortable viewing when the telescope is pointed at, or near, the zenith (i.e. directly overhead). The resulting image is the right way up, but is reversed from left to right.
Star diagonals let you view objects at a 90° angle from the direction the telescope is pointing, which means viewing will be much more comfortable, especially when the telescope is pointing straight up.