The SureFire X400 WeaponLight

     Since introducing its first laser sight and weapon light in the 1980s, SureFire has set the standard by which weapon lights are judged. Now, the Fountain Valley, California, company redefines that standard with the X400, a tactical light that integrates a versatile high-output LED and visible targeting laser into a compact single unit.

LEDs vs. incandescent bulbs

     The SureFire X400 utilizes a state-of-the-art CREE LED (Light Emitting Diode). LEDs are based on solid-state semi-conductor technology. Unlike incandescent bulbs, they have no filament to burn out or break. They are also exceptionally power efficient, consuming 1/10 of the power of an incandescent bulb, enabling them to run longer.

     Recoil is the enemy of the filament in incandescent bulbs. LEDs are inherently more shock resistant, making them immune to the effects of recoil.

     SureFire considers 60 lumens to be the tactical-level threshold for an incandescent light. The tactical-level threshold for white LED light is 50 lumens, due to its higher color temperature. Of course, there's more to a tactical light than just light output. The ideal tactical beam has a bright center spot that provides a blinding beam surrounded by a soft corona of peripheral light to provide a search beam more suited for close-up operations. This isn't a problem with an incandescent bulb with a properly designed reflector, but LEDs are another matter.

     Unlike incandescent bulbs, which have a spherical radiance, LEDs radiate their light in a 180-degree forward arc. There are two options — use a lens to achieve a more concentrated central spot of light, or use a specially designed reflector to achieve some degree of peripheral light around a bright center.

     The X400 features a computer-engineered focusing lens with Total Internal Refection (TIR) to provide a tightly focused central bream and an enhanced peripheral corona. This lens allows the X400 to project a tightly focused beam at greater distances than comparably sized lights while at the same time producing a wider corona to accommodate peripheral vision.

X400 details

     The X400 is designed for close-quarters and longer-range applications. It's identical in white light performance to the X300 WeaponLight.

     The beam from the X400, provided to Law Enforcement Technology testers for evaluation, was flawless. The tactical light produced a bright central beam with a wide background beam. The beam was even and well focused, without any rings or dark spots. The CREE LED produces a brilliant white beam.

     The company rates the X400's output at 110 lumens. SureFire is conservative in these ratings. The company measures lumen output out the front of the light after losses from the lens and reflector are accounted for. In contrast, some manufacturers measure output at the emitter before losses are accounted for or simply use the LED's maximum rated output.

     The X400's bezel window is constructed of tempered Pyrex glass for scratch-resistance and LED protection. Its thin, anti-reflective coating maximizes light transmission.

     The lifetime of a CREE LED is rated at thousands of hours. For purposes of comparison, incandescent bulbs have a rated life of approximately 30 hours.

     The X400 has a 635nm (red/orange) continuous wave (non-pulsing) ANSI Class IIIR (FDA Class IIIa) laser. The laser has a 5mW peak output. The laser aperture has a glass aspheric lens. The beam is tightly colimated for maximum power density. Dot size is approximately 0.5 inches at 50 feet. The laser on the X400 is fully adjustable for both windage and elevation with recessed Allen screws. The laser holds alignment to within one MOA.

     This tactical light features a five-position rotary mode selector mounted at the rear of the laser housing. It allows the operator to choose between disable, white light only, laser and white light, laser only, and disable as the tactical situation dictates. Positive detents provide secure, tactile selection.

     The X400 is powered by two 3-volt 123A lithium batteries, which are included. The X400 has a runtime of 2.4 hours of tactical-level white light on a set of batteries. For purposes of comparison, a 6-volt SureFire light with the 120-lumen P61 incandescent lamp assembly has a runtime of 20 minutes.

     The light is built to military specifications. It features a precision-milled aerospace-grade T6-AL aluminum body with a Mil-Spec Type III hard-anodized black finish. The rails and rail adapter, machined from the same aluminum, are a nice upgrade to the X300. The X400 is O-ring and gasket sealed, making it waterproof to a depth of 66 feet.

     The X400 measures 3.54 inches long by 1.56 inches wide by 1.86 inches high (with standard switch) and has a 1.06 diameter bezel. Its total weight (with batteries) is 4.4 ounces or less than a loaded pistol magazine.

Switching options

     SureFire's new offering features digital current regulation to maintain a consistent light output throughout the useable life of the batteries. The X400 also has a modular switching system with several switching options available.

     This tactical light comes with an ambidextrous toggle/momentary pressure switch that provides momentary and constant-on activation. For constant-on operation, press the switch up or down. For momentary activation, push the switch forward. It's easily operated with the trigger finger in an indexed position (Uniform Cover Position) or with the thumb of the support hand. Momentary operation of the X400 requires the shooter to use his support hand when firing unless a remote pressure switch is employed.

     Weapon-specific Dev Group (DG) remote switches for a variety of popular service pistols are available from SureFire for the X400. The DG Remote Tailcap Switch enables light activation with a center-mounted pressure pad on the handgrip's front strap. This gives the user precise control without altering his weapon grip.

     SureFire is also developing different switching options for use on shoulder arms. The waterproof XT-07 Rail Mount Tape Switch is an example. The XT-07 includes a disable feature, constant click on/off push button, and a momentary-on tape switch attached via a 7-inch cable connected to a replacement tailcap. Simply pop off the standard rocker switch tailcap and pop on the XT07. The tape and rocker switches are integrated onto a molded urethane brace that is flexible enough to snap onto a Picatinny rail. The constant-on push-button switch and momentary tape switch operate independently.

Integrated rail system

     The X400 is designed to fit the Picatinny rail and the Universal Standard rail. The X400 mounts on the weapon using a Nylok screw clamp mount. It's a very solid mount that provides excellent boresight repeatability, and although it sacrifices the quick detach and quick installation of a lever latch, it takes little time to install and remove. The X400 includes interchangeable spacer blocks for Universal and Picatinny rails because Universal and Picatinny rails have different specifications and require different adapters for a proper fit.

     The X400 provides a superb light and laser for long guns when employed with the XT-07 removable tape switch module for the X-Series. The X400 is especially suited for use on compact assault rifles, PDWs, SMGs and pistol-caliber carbines. The integrated system eliminates the "module stack up" that would be the case where a separate laser sight and illuminator are employed.

     The era of LED lighting is upon us. Australia has banned the sale of incandescent bulbs after 2010. The U.S. Department of Energy predicts affordable, efficient LED lamps will be lighting everyone's homes by 2025. Cities around the globe have already saved millions by replacing fluorescent and incandescent lights with state-of-the-art LEDs. And now SureFire has revolutionized law enforcement tactical lighting by producing a flashlight that combines a targeting laser with a high-output LED.

     Eugene Nielsen is a private consultant. The former police officer can be reached at