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. ACOG 4x32 Scope with Green Horseshoe BAC Reticle- includes Flattop Adapter. Features dual illumination (Fiber optics provides daylight illumination and tritium illuminates reticle at night). The ranging reticle is calibrated for 6.8 SPC flattop rifles out to 800 meters.