The rugged Surefire X300U-B Ultra with its T-slot thumbscrew clamp attaches securely to the Universal and Picatinny rails (fitting more models than ever before) found on most handguns, and it will fit many popular rail-less handguns by using SureFire's MR adapter mounts. As always for this best-in-class model, it features integral onefinger ambidextrous momentary- and constant-on switching and can be equipped with SureFire's optional DG handgun grip switch. This versatile Weaponlight also attaches to the Picatinny rails on long guns-more securely than ever before-and can be activated via an optional XT remote switch that gives you precision control of Mfg: Surefire