Astromania Finderscope Starpointer for Astronomical Telescopes With Slide-in bracket A small red LED dot is projected onto a non-magnifying viewing window so you can aim the main telescope quickly and easily. Thumbwheels allow positioning of the red dot horizontally and vertically for precise telescope alignment. Brightness of the red dot is adjustable to suit your preference. Requires CR-2032 lithium button-cell battery (Not Include). Simple, affordable, and effective red dot sighting device makes aiming your telescope a cinch! Includes bracket that fits the dovetail mounting base on many telescopes