The NcStar AR-15 Detachable Rear A2 Iron Back-up Sight (dual aperture) is precision-made with aluminum and steel. The fixed A2 design is adjustable for windage and elevation and it mounts onto Weaver and Picatinny-type rails. Type Rear Style Dual Aperture Series Rear Sight Firearm Fit AR-15 Frame Color Black Front Color N/A Firearm Type AR Platform Rear Material Steel Frame Material Aluminum/Steel Front Material N/A Base Configuration Picatinny Rail Windage Adjustment Adjustable Elevation Adjustment Adjustable