Trijicon ACOG Rifle Scope, 5.5X50, Red Chevron Reticle .308, Includes Flattop Adapter, Matte Finish TA55A The Trijicon ACOG (Advanced Combat Optical Gunsight) is a fixed power, compact riflescope with an illuminated reticle pattern for use in bright to low/no light. The ACOG is designed to be extremely durable and reliable. Combining traditional, precise distance marksmanship with CQB speed, many variants include a bullet drop compensated (BDC) reticle. Every feature of its design was chosen for a single purpose: to provide increased hit potential in all lighting conditions.