G&G GGG-1281 Spring Actuated Flip Up Front Sight for Dovetailed Gas Blocks The gg&g spring actuated flip up front sight is easy-to-install Solid squeeze rail attachment mechanism Manufactured specifically for dovetailed gas blocksthat are lower than a Mil-Spec flat top upper receiver It provides the same command front sight height as that of a back up iron sight when it is mounted to the Flattop receiver Provides "true center" co-witness with most Red dot optics