Trijicon 100553 ACOG ECOS 4x32mm Illuminated Red Crosshair .223 BDC Combo - Flat Dark Earth

The Trijicon 100553 ACOG ECOS pairs the battle-proven 4x32 ACOG riflescope with a top-mounted Trijicon RMR2 red dot in a single, purpose-built Flat Dark Earth combat optic system. Designed as a one-optic solution for the modern carbine, the ECOS (Enhanced Combat Optical Sight) gives the shooter instant, eyes-open transition from a magnified illuminated reticle out to extended range to a parallax-free 3.25 MOA dot for fast close-quarters engagement.

At the heart of the system is a fixed 4x ACOG built around a forged aluminum housing in a non-reflective Flat Dark Earth finish, with multi-coated lenses that deliver a crisp sight picture and excellent low-light transmission. The optic is waterproof to 11 meters and is also fog and shock resistant, built to the same rugged combat standard as every Trijicon ACOG in service with U.S. and allied military forces.

The dual-illuminated red crosshair .223 BDC reticle uses both tritium and fiber optic elements that automatically adjust brightness to ambient light, so the optic is always ready day or night with no batteries required. The BDC ladder is calibrated to the .223 Remington / 5.56x45mm NATO trajectory for bullet drop compensation at extended ranges. Adjustment is set to 2 clicks per inch at 100 yards, and the ACOG delivers a generous 1.50" eye relief with a 36.80 ft field of view at 100 yds.

Mounted piggyback on the ACOG is a Trijicon RMR2 reflex sight with a 3.25 MOA red dot, giving the shooter a true co-witnessed CQB aiming solution without removing the magnifier from the fight. The package also includes a set of backup iron sights and a quick release mount for fast, repeatable attachment to any standard flattop Picatinny rail, making this a turn-key optic setup for AR-15, M4, and M16 platforms.

Compact at just 6.20" overall (ACOG body) and 15 oz, the ACOG ECOS combo delivers magnified precision, an instant red-dot option, and all-weather durability in a package purpose-built for duty, defense, and hard-use carbine applications.