The Trijicon 4x32 ACOG ECOS is a different animal from the standard ACOG lineup - and deliberately so. ECOS stands for Enhanced Combat Optical Sight, and the TA01-D-100555 is built around a specific operational need: a magnified primary optic that keeps fully functional backup iron sights accessible without removing anything from the rifle. The integrated iron sights fold flush when not needed and deploy instantly when the situation demands a failsafe aiming solution. The amber crosshair reticle on this Trijicon ACOG TA01 occupies a unique place in the reticle color spectrum. Amber sits between red and green in terms of eye sensitivity, giving many shooters a reticle that's easier to track across a wider range of lighting conditions than either color alone. The crosshair pattern suits precision-oriented shooting, where a clean, symmetrical aiming point matters, and the 5.56 calibration builds bullet-drop compensation directly into the stadia lines for accurate distance holds without mental calculation under stress. The quick-release mount on the Trijicon ACOG 4x32 with RMR-compatible platform lets you dismount and remount the optic without re-zeroing. For shooters who move between rifles, share equipment, or need to transition to a backup system fast, this is a practical feature that earns its place in the field rather than just on a spec sheet. Most optics force a choice between magnification and backup sights. The ACOG ECOS removes that compromise entirely - 4x magnification, integrated irons, quick-release mounting, and Trijicon's battery-free dual illumination in a single forged aluminum housing. Features: Magnification - 3x - 6x Size - 32mm - 48mm Weight, 7.7 oz - 39.3 oz Fiber Optics and Tritium Illumination Source Reticle Pattern - Crosshair, Chevron Day Reticle Color - Red, Green, Black, or Amber Night Reticle Color - Red, Green, Black, or Amber Housing Material - Forged Aluminum Mount Options - TA75, TA51, Quick Release Calibration - .50 BMG, .223 Trijicon 4x32 ACOG ECOS Illum Amber Crosshair 5.56 Reticle w/Iron Sights QR Mount - LED 3.25 MOA Red RMR Type 2 - FDE TA01-D-100555