The one that started it all. The concept was simple; a durable scope with a reticle that illuminates in low-light and no-light situations—without requiring the use of batteries. More than 30 years later, the original ACOG stands the test of time as one of our most popular items. Choose from many 4x32 options, including the Official Rifle Combat Optic (RCO) of the U.S. Marine Corps.