Magpul Industries MBUS Back-Up Front Sight 
 
Spring loaded flip up sight
Easily activated from either side or by pressing the top
Protective wings shield the spring-locking A2 front sight post
Polymer construction provides light weight and resists abuse
Detent and spring pressure keeps sight in place but allows for unobstructed folding under impact
 
 
Product Description
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.