Polar alignment scopes are small telescopes or tubes used for aligning your telescope with the North or South celestial pole, which is necessary in order for the telescope to consistently track the stars. Accurate tracking is an absolute must for long exposure astrophotography to keep the image from becoming blurred. It also makes slewing and tracking much easier during normal visual observation because you can hunt down those pesky smaller and fainter objects instead of reaching the supposed locale and focusing to see nothing at all.
The EZAlign™ from JMI Telescopes allows a telescope to be quickly and easily aligned with the North or South pole. A time-consuming initial alignment must be made using the star drift method. Subsequent later alignments will be as good as this initial alignment, but far less time-consuming. You'll simply rotate the scope to align the constellation reticle with your naked eye's view of the sky, then adjust the telescope mount to align two stars with the reticle. The reticle illuminator includes an automatic shutoff feature.