ARO Red Dot SightHolosun ARO CORE Red Dot SHAKE AWAKE RED DOT 50,000 HOUR BATTERY The ARO enclosed rifle sight delivers both eyes open, fast engagement functionality with no parallax, unlimited eye relief, and a dozen brightness settings. Pick up your rifle and the dot is already on. Set it down and it shuts off. That's Shake Awake no buttons, no thinking, just a crisp red dot ready when you are. One CR2032 battery runs for over five years. Swap it from the side