The C4 Sight Combo uses Dynalign Technology to deliver a superior sighting system. The innovative four concentric circles create a sight picture that optimizes accuracy. - C4 Front Sight Features: - Outer and inner concentric circles for easy target acquisition - Windage adjustable for zeroing on the front sight which guarantees that the rear sight windage is perfectly centered when at zero for maximum in windage adjustment in either direction along with easy return to zero - Tool-less elevation adjustment that is always perfectly concentric with outer circle - Aperture sight gives a shooter the ability to focus 100% on the target - Strategic use of materials to maximize strength and weight - C4 Rear Sight Features: - A purely concentric sight picture with an inner aperture and outer circle for easy alignment - Rapid windage and elevation adjustments - Elevation adjustment to 600 yards - Elevation cam for most ballistic bullet paths available - One-handed deployment and stowage - Interchangeable Apertures .70 .50 and a ghost ring - Spare aperture conveniently stores into windage knob - Strategic use of materials to maximize strength and weight - DYNALIGN TECHNOLOGY: Concentric Sight Picture - Most BUIS systems utilize a sight picture that is non-intuitive. - The brain