Rifleshooter.com reviews the Surefire X300
The Surefire X300 (152-000-041) is an LED tactical light, powered by two 123A batteries, that is mountable to a series of rifles, shotguns and pistols. The unit simply slides onto the rail and is quickly removable by the user. The light has a rugged LED lamp and a 170-lumen output with a 2.4 hour run time and includes adapters for various handgun rails as well as the standard weaver rails found on many long guns.
This light is actuated by an ambidextrous lever located on the rear of the housing; with the lever in the center position, the light is off. When the operator moves the lever either up or down, the switch is activated and the light comes on. It is worth noting that unlike some other models that provide a momentary feature in one direction and a constant-on in the other, the Surefire is constant-on in both directions.
As with all Surefire products, you get what you pay for. The fit and finish are exceptional. The 170-lumen LED light is crisp and bright without any shadowing. Most of the users who tried the light liked it a lot; the constant-on feature was especially useful when the host weapons recoiled.
This compact, lightweight, and powerful light comes highly recommended.
The Surefire X300 is available from Brownells (152-000-041)