The HS510C Open Reflex Sight with Circle/Dot Green Reticles has an open frame for a wide sight picture. 
It is powered by a CR2032 batter with Holosun's innovative Solar Failsafe back up. 
Equipped with Multi-reticle system, the green reticle can be switched between a 65 MOA circle with 2 MOA dot, a 2 MOA dot only, or a 65 MOA ring only at the push of a button. Better yet, the same LED projects both reticles, so no re-zeroing is necessary.
Multiple Reticle System featuring 3 reticles
Parallax-free & Unlimited Eye Relief.
Minimized obstruction of vision with push button controls and a streamlined housing design.
Motion Sensor with Shake Awake or can stay on until manually turned off.
Solar cell and high capacity battery provide dual power supplies