The first weapon-mounted lights weren't particularly user-friendly. The jury-rigged units SWAT cops bolted on their entry guns were effective, but they were too cumbersome to be of use to the armed citizen or patrol officer. However, those elite units quickly proved that the tactical and safety advantages of weapon-mounted lights were too many to ignore.

Today's shooters have a much greater selection when it comes to size, quality, features and mounting systems than I ever thought possible when those first lights came on the scene. Unfortunately, there are so many choices that selecting the light that best fits your needs and your pistol can be confusing.

The first thing to consider when selecting a weapon light is what type of rail your pistol has. If your pistol has the Universal Standard Rail, a light made for Picatinny-spec rails won't fit correctly. SureFire's new X300 comes with an adapter for both systems, while Insight's SSL-1 has an adjustable rail interface. Insight Technologies' M3 and M6X lights may be ordered with one of four rail interfaces, including the new S&W rail and Insight's flexible Rail Grabber interface.

Keep in mind that if your light is not designed for your rail, you may be able to install it, but it won't fit properly. Make sure you get a light with the correct interface.

If your pistol doesn't have a rail, you're not out of luck. Dawson Precision and SureFire, for example, make good aftermarket accessory rails for some Beretta, SIG and HK models, as well as 1911s.

Size should be your next consideration. Most lights are perfectly suitable for the majority of pistols, but a more compact light, such as Insight's X2, is a better fit for smaller guns such as Springfield's Micro-Compact. A bigger light will work, but compact lights sacrifice little in terms of performance and look better on smaller guns.

Once you decide on a package, you have to decide what level of performance you need. Here, two factors--light type and brightness--are closely related.