The SI strike rail was developed to fulfill the requirements of certain agency partners, who wanted a lightweight, but feature packed rail that they could depend on when entering harm's way. In service of this mission, we bring to you, the new SI Strike Rail. Lightweight, high strength, everything you need, and nothing you don't. Features: 1.57 inches internal diameter for suppressor or oppressor compatibility For AR-15 style rifles only, not compatible with AR-10 receivers, MLOK compatible Ambidextrous QD socket placement Built-in anti rotation feature in rail Reinforced steel mounting nut and bolt