This precision made AR15 Flip Up Front Sight will fit virtually all AR-15 Picatinny rail gas blocks. The 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 for long lasting durability. Length: 1.2” extended, 2.1” folded. NcSTAR Limited lifetime warranty.