Magpul MBUS Front Flip Sight Gen 2

Magpul Industries MBUS Back-Up Front Sight Gen 2, Fits Picatinny Rails, Flip Up. Available in Black, Flat Dark Earth, and Olive Drab Green.
The MBUS (Magpul Back-Up Sight) is a low-cost, color injection molded, folding back-up sight. The MBUS Front Sight is adjustable for elevation and fits most 1913 Picatinny-railed hand guards, but is specifically tailored to the AR15/M16 platform.