tactical rail

A tactical light or weapon light is a flashlight used in conjunction with a firearm to aid low-light target identification, allowing the user to simultaneously aim a weapon and illuminate the target. Tactical lights can be handheld or mounted to the weapon with the light beam parallel to the bore. Tactical lights can also serve as a non-lethal weapon, used to temporarily blind and disorient targets or, in the case of a large handheld flashlight, to be used as a blunt weapon.
Features particularly associated with tactical lights include shock resistance, reliability, lightweight construction and powerful, long-lasting batteries, and high light intensity. Tactical lights may have optional filters to produce colored light, to not attract bugs, or may emit only infrared radiation for use with night vision equipment. A laser sight may also be added to a weapon-mounted tactical light.

View More On Wikipedia.org