Some of the red dots and rifle scopes with reticle illumination have Auto – TurnOff function. This means, in case that you forget to turn off illumination or when you leave your firearms on table (you don’t do any movements with rifle scope), illumination automatically turns off. The time when illumination turns off is different from rifle scopes to rifles scopes.
Many of the expensive and high quality rifle scopes with illuminated reticle have an Auto-TurnOff smart motion sensor that detects different angles and automatically turns OFF or even ON the illumination of the reticle, based on the rifle scope position.
This is a nice feature to have, because this increases the battery life.