This is a Magpul Industries Sight known as the MBUS, model MAG247-GRY.
The MBUS (Magpul(R) 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.
Features:
Polymer construction
Spring-loaded flip up sight
Protective wings shield the spring-locking A2 front sight post
Elevation adjustment tool included
