The 4.0" 38mm Combat Red Dot Sight is loaded with ultra-cool features.  Great Field of View and Unlimited Eye Relief.  Clear and Sharp 4.0 MOA Dot Sight.  No-Reflection High Tech Emerald Coatings.  Red or Green Dot Adapts to Any Environmental Background.  Optimal Height Design to Co-witness with Iron Sights.  Includes Both High Profile Cantilever Mount and Low Profile Vertical Mount with Innovative Quick Detach Mounting Deck to Use on Any Picatinny Rail.  Patterned Illumination Rheostat with Variable Brightness Levels Offers Stealthy and Infinitely Fine Adjustment.  Aim and Instant Lock On Target to Enhance Shooting Accuracy and Performance.