The Trijicon Acog 4x32 Dual Ill Red M855 Rco TA31-D-100582 is an Advanced Combat Optical Gunsight designed for M16A4 and M16M4 platforms, delivering precise 4x magnification on a durable forged aluminum housing with a compact 6.0-inch length and 14.2 ounces of weight for dependable field performance. Its dual illumination technology blends fiber optics with self-luminous tritium, ensuring the red daytime reticle and nighttime aiming point remain visible without batteries, while the fiber optic system automatically adjusts reticle brightness to ambient light conditions, enabling operators to keep both eyes open and maintain maximum situational awareness. The horseshoe with dot reticle, complemented by the Target Reference System, supports rapid target acquisition at close ranges and improved identification and hit probability at extended distances out to 1000 meters with the Bullet Drop Compensator. External windage and elevation adjustments remove the need for tools, and the design is waterproof up to 11 meters without caps. This package includes a LaRue LT799 mount, along with external adjusters, caps, a lanyard, and accessories, all calibrated for 0.223 at 14.5 or 20-inch barrels, with 1.5 inches of eye relief and an 8 mm exit pupil to support versatile field use.