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. Features:Impact resistant polymer construction provides light weight and resists operational abuseSpring-loaded flip up sight easily activated from either side or by pressing the topDetent and spring pressure keeps sight erect but allows for unobstructed folding under impact, etc.Clamps to most any MIL-STD-1913 Picatinny/STANAG 4694 railed hand guard and provides the same height-over-bore as standard A2 ironsProtective wings shield the spring-locking A2 front sight postElevation adjustment tool included, but most aftermarket A2 front sight adjustment tools may be used as wellSpecifications:Weight, w/ hardware: 1.2 ozHeight above rail, stowed: ~0.51"Length, stowed: 2.6"Length, deployed: 1.5" Made in the USANOTE: Cannot be mounted to a railed gas block due to excess heat issues. Front MBUS must be mounted to a railed fore end on the same plane as the receiver rail. Because of this the sight is also not compatible with MOE Hand Guards.