C-MORE Systems red dot sights encapsulate the light source in a separate diode module. These modules are interchangeable in all C-MORE full size sights (NOT STS or RTS2), providing each sight with the ability to utilize different size dots for different applications. The size of the dot is measured in minutes of angle (moa), with 1 minute of angle being equal to 1 inch @ 100 yards (approx.). Example; a 2 moa module will produce a dot that will cover 2 inches of your target @ 100 yards, a 6 moa module will cover 6 inches, and so on. When you reduce the target distance by half, you also reduce the minute of angle by half. Example; the 2 moa module will cover 1 inch @ 50 yards, the 6 moa m Mfg: C-More Systems