The NcSTAR MARFLF 223/556 Flip Up Front Sight Back-Up Sight AR15 is an indispensable addition for AR-15 enthusiasts, providing reliable back-up iron sight functionality. Engineered for precision, this sight effortlessly mounts on gas blocks featuring lower Picatinny rails, ensuring an unobstructed view of your optics when folded. AR-15 Flip-Up Front Sight - Back-Up Iron Sight Compatible with Gas Blocks having Lower Picatinny Rails Innovative Flip-Up A2 Front Sight Post for Easy Storage Elevation Fully Adjustable for Precision Shooting Robust Aluminum and Steel Construction for Durability Compact Size: 1.2" (extended), 2.1" (folded) Lightweight at just 3.4 oz for Enhanced Mobility Maximize your shooting experience with the NcSTAR MARFLF Flip Up Sight, designed for performance and convenience.