The A.R.M.S Gas Block with Flip-Up Front Sight has the shape we all know and love, but it also folds and deploys using only a finger of one hand. It's extra rugged via the support angle, plus all the other features of the great conventional non folder. It also uses the standard front sight bead, and or night sight posts. It is barrel mounted into place, via the included allen wrench. FeaturesFlip-Up Front SightBayonet LugStandard Front Sight BeadExtra Rugged Construction