Surefire X300V-B Vampire Weaponlight. White/Infrared.
Surefire X300 Vampire Weaponlight, 350 Lumens, Universal/Picatinny Rail Mount, Z-XBC Push/Toggle Switch, Black Finish X300V-B
The -B at the end of the model designates that this light uses the screw mount, as opposed to the clamp-mount. For this reason, it may have some difficulty fitting in some holsters