The Trijicon SRS (Sealed Reflex Sight) represents the highest level of performance in sealed reflex sights. By combining the most advanced technology and design features, the SRS establishes a new standard. The SRS features a compact body without compromising the durability you expect from Trijicon. The short body also eliminates tube effect that is common of other tube-style red dot sights. The 28mm aperture lends itself to a generous field of view and extremely quick target acquisition and the 1.75 MOA dot features ten brightness settings to match any situation. One added feature of the SRS is a truly innovative photovoltaic solar cell that acts as the primary power source during daylight conditions. A single AA lithium battery will exceed 3-years of continuous use thanks to the technology in the SRS.