The 518 sight features side button functionality. It's also compatible with the drop-in Laser Battery Caps that EOTech designed to enhance aiming through the use of visible and IR lasers.-0 68 MOA Ring w/ 1 MOA DotDimensions: 5.6"L x 2.2"W x 2.9"H (142.3 x 55.9 x 73.7mm)Weight: 13.8 oz / 391.2 gWater Resistant: Submersible to 10 ft./3 mMount: 1" Weaver or MIL-STD-1913 RailBrightness: 20 settingsPower Source: AA (Alkaline or Lithium BatteryBattery Life: Approximately 1,000 continuous hours (Lithium) or 600 hours (Alkaline) at nominal setting 12 at room temperature