This is a Ultradyne USA Sight known as the C4, model UD10480.
The C4 Front/Rear Sight Combo is a dual aperture sighting system that is changing the way shooters think about iron sights. The C4 Rear Sight offers Rock-solid performance in a compact form with a ballistic ally calibrated elevation system that adjust in 50-yard increments from 200 to 600 yards. The C4 Front Sight brings precision front aperture technology to backup iron sights along with the ability to adjust both windage and elevation. Using these sights together creates a perfectly concentric sight picture that allows the shooter to see the target" enables faster sight acquisition and gives the ability to consistently shoot accurately out to 600 yards and beyond. All with compact" foldable iron sights.
Features:
Rear sight 1.38 wide and .369 tall when stowed front sight 1.21 wide and .369 tall when stowed;Mounts to any Mil-STD 1913 picatinny rail