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. With the Trijicon ACOG 3.5x35 LED riflescope" 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). Like all ACOG models" the 3.5x35 LED is designed with a forged 7075-T6 aircraft-grade aluminum alloy housing" making it nearly indestructible. Includes a TA51 Flat Top mount.