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. The original Trijicon ACOG delivers unprecedented performance and durability with total user illumination control. Now with six levels of brightness" thanks to the ACOG 4x32 LED. Users can select from six adjustable brightness levels with an "off" between each setting" allowing the user to determine how much to illuminate the reticle - even in transitional lighting. Powered by a single AA battery" the LED ACOG can run for over 12"000 continuous hours (on setting #4). Includes a TA51 Flat Top mount.