A holographic sight system is a combination of a scope and open sights. It combines the best of both worlds for target acquisition. A holographic sight system looks similar to a scope but has no magnification and can be used with both eyes open. It offers the fastest sight acquisition time of any sight type and is used by the military on the M4 and M16A2. It is a durable and compact sight system that works extremely well in bright light and low light. The reticle brightness is adjustable for various lighting conditions. The EOTech 516 is battery (2 CR125) operated and is rated for 1100 hours.
EOTech is one of the top manufacturers of holographic sight systems and has been chosen by the military. They are rugged and reliable.
EOTech 516 Holographic Sight System Review