With the hws 518 the best just got better.Get all of the features found in eotechs top sight the exps but with easy-to-find aa batteries.The 518 has buttons on the side that allow the user to position it close to the magnifier to reduce rail space.Left side buttons reduces rail space when partnering with a magnifier.Features auto shut down at 8 hours.Battery Size: AAMagnification: 1xObjective: 1.20" x 0.85"Field Of View: 30 yds @100 ydsEye Relief: UnlimitedDot Size: 1 MOA/68 MOALength: 5.60"Weight: 13.80 ozFinish: Matte BlackReticle: 1 MOA Red Dot/68 MOA RingAdjustment Size: 0.50 MOAProofs: Weather Resistant/Water ResistantOptic Coating: Anti-ReflectionWindage Elevation: Adjustable