Features: AR-15 Flip-Up Front Sight - Back-Up Iron Sight Designed to be Mounted on Top of Gas Blocks with Picatinny Rails lower than the AR15 Receiver Rail Flip-Up A2 Front Sight Post folds down out of view of your optics when not in use The A2 front sight post is fully adjustable for elevation Aluminum and Steel Construction Length: 1.2" (extended), 2.1" (folded) Weight: 3.4 oz