The AN/PEQ-2 has two infrared laser emitters—one narrow beam used for aiming the rifle, and one wide beam used for illuminating targets, like a flashlight. The beams can only be seen through night vision goggles. Each beam can be zeroed independently, and the illuminator's radius is adjustable. The two lasers are tied into one 6-mode switch, which has the following modes:
|Mode||Marking||Targeting laser||Illumination laser|
|1||AIM LO||low power||off|
|2||DUAL LO||low power||low power|
|3||AIM HI||high power||off|
|4||DUAL LO/HI||high power||low power|
|5||DUAL HI||high power||high power|
Turning the mode switch does not turn on the lasers. A recessed button on top of the device is tapped once to briefly turn on the lasers or tapped twice to turn the lasers on until deactivated, either by pressing a third time or by turning the mode switch to off. Additionally, an extra pressure switch can be plugged into the rear of the device and then placed virtually anywhere, limited only by the length of the pressure switch's cord; typically one to two feet. This pressure switch operates the same way as the recessed button.
The AN/PEQ-2A upgrade incorporates a safety block which physically prevents turning the mode switch to any of the high power modes, which are capable of causing eye damage. Both variants are waterproof to a depth of 20 meters and run on two AA batteries. Additional civilian variants also exist—they can provide greater power, visible/IR laser combinations, or other features.