The inherent problem with red dot sights is that they are electro-sights and require a battery to function. Batteries die and electronics can fail, but the Trijicon RMR Dual Illuminated Reflex ...
You can pick up a reasonable sight for about $100 or so, including one to mount on a defensive ... and the Trijicon RMR Type 2 got the nod as the overall best red dot sight. For starters it ...