The FN M16A4 would officially replace the M16A2 as the USMC standard service rifle in 1997. With a Picatinny upper receiver and Knights Armament quad rails, the M16A4 would provide the Marine Corps with the ability to add infrared aiming devices, flashlights and optics to their service rifles. While implementation of the “A4” would not begin in large quantities until after the beginning of the Global War on Terror (GWOT), the design would become synonymous with the Marines during this timeframe.