Pentax Gameseeker RD10 Dot Sight3 7 8" overall. 4 MOA dot is the ideal size for most shooters. High quality optics with fully multi coating on every surface. 11 brightness settings for various shooting conditions. Uses one CR2032 battery which provides 72 hours of continuous use. PentaBright Technology gives a sharp, clear image. Parallax free for accurate target acquisition. Features an integral mount that is designed for ease of use with any standard Weaver base or 3 8" base.