2X42AR red dot sight is built with unique 2x magnification adapter. With the 2x adapter detached, it can be used as a standard 1x42 red dot sight. The sight also uses more visible "CQB" dot illuminated in Green and Red lights. It has integrated reversible Weaver/.22 mounting rails adjustable to fit onto standard Weaver or .22 dovetail base. The sight has a "CQB" Tac dot which is much easier to center than a small round dot you normally see on such sights. Overall Length: 5 3/8". Uses one CR2032 button cell battery(included). Aslo included with the sight are flip lens covers.