ACOG

The Advanced Combat Optical Gunsight or ACOG is an attachment featured in the upcoming first person shooter, Battlefield 3. It operates on illuminated Tritium decaying withing the sight. The magnification can range from 1.5x to 16x.

Battlefield 3
The ACOG sight is seen on the M16 and AK-74 in pre-release game play. It functions similarly to the 4X Rifle Scope from previous games. It is unknown if it will replace the 4X Rifle Scope, or will be featured along with it.