The TA31RCO is an Advanced Optical sight (ACOG). It incorporates dual illumination technology using a combination of fiber optics and self-luminous tritium. This allows the aiming point to always be illuminated without the use of batteries. The tritium illuminates the aiming point in total darkness, and the fiber optic self-adjusts reticle brightness during daylight according to ambient light conditions. No tools are needed for windage and elevation adjustments because the TA31RCO features external adjusters, making it waterproof up to 11m without the caps. Mounting bosses are integrated into the housing by the eyepiece to allow the easy addition of a Trijicon RMR (not included).
Stay tightly focused on your target in any conditions with the Trijion ACOG 4x32 combat riflescope. Designed for the M150 rifle, the scope features an aircraft aluminum alloy housing that's nearly indestructible, so you can use the scope for years (or decades) to come. The ACOG 4x32 scope also makes aiming a cinch thanks to the Bindon Aiming Concept (BAC). Trijion ACOG models equipped with BAC allow you to aim using the both-eyes-open method, helping you acquire your target quickly in any light. Add in such details as broadband, anti-reflective multicoated lenses and a Tritium phosphor lamp and you're virtually guaranteed to see your target even at dawn or dusk. The broadband lenses provide superior clarity and light gathering capabilities with zero distortion, while the Tritium phosphor aiming reticle glows brightly in low-light conditions, and is guaranteed to illuminate for up to 15 years. The scope even offers Trijicon fiber optics, which automatically adjust the brightness level and contrast of the reticle depending on the available light.
Other details include a maximum eye relief; a large exit pupil for faster target acquisition; a rugged internally adjustable design; a dry-nitrogen-filled housing to prevent fogging; and a waterproof build to 100 feet. Completely battery-free, the ACOG 4x32 scope comes with a TA51 thumbscrew flat-top mount adapter, a storage pouch, an Army RCO KillFlash, a set of flip caps, an adjuster cap lanyard, a LensPen cleaner, a logo sticker, and an instruction manual.
Specifications:

Magnification: 4x
Objective lens diameter: 32mm
Bullet drop compensator: Yes
Illumination source: Fiber optics and Tritium
Reticle pattern: Chevron with target reference system
Day reticle color: Red
Night reticle color: Red
Calibration: .223
Bindon aiming concept: Yes
Eye relief: 1.5 inches
Exit pupil: 8mm
Field of view: 36.8 feet @ 100 yards
Adjustment: 2 clicks/inch @ 100 yards
Tube size: N/A
Mount: TA51
Housing material: Forged aluminum
Length: 7.3 inches
Weight: 16.2 ounces
Warranty: Lifetime