Strike Industries’ Strike Rail is a lightweight but feature-packed rail that you can depend on when entering harm’s way. Its 1.57″ internal diameter is for a suppressor or Oppressor compatibility. The rail is M-Lok compatible has a built-in anti-rotation feature in the rail ambidextrous QD socket placement and reinforced steel mounting nut and bolt. It is not compatible with most gas piston systems. This 15.5″ model has a blue finish.