DI Optical RV2 Raven Series Red Dot Reflex Sight with 3 Push Buttons Brightness Control and Auto Shut-Off 1.5 MOA Dot Size with Large 30mm Objective Lens 14 Brightness Setting (7 Daytime & 7 Nighttime) CNC Machined from Solid Billet 6061-T6 Aircraft Quality Aluminium for Maximum Durability Approximately 20,000 Battery Life with 1-AA Battery (Mid Brightness Level) Auto shut-off feature (approximately in 10 hours) to save battery