GMG AR15/M4 Aluminum Quad Rail: * The GMG AR15/M4 Aluminum Quad Rail locks firmly in place when tightened, eliminating any hint of side to side slop * AR15/M4 Rail from GMG has notches that run the full length of the quad rail in order to provide extra strength and rigidity effectively eliminating any flex or torsion in, providing a stable mounting platform capable of maintaining zero on even the finest of optics * Solid aluminum 2-piece construction * Black anodized * Easy to install * No gunsmithing necessary * Maintains zero on optics