The SureFire 321LM replaces the original forend of your Mossberg 500 shotgun with a 14" barrel or 6 3/4" forend tube. Extremely compact 3-volt (1-battery) system features a virtually indestructible LED emitter focused by a TIR lens, which produces a brilliant beam optimized for close- to medium range applications. Two switches are integrated into the forend: a momentary-on pressure pad switch (right side) and a constant-on rocker switch (left side). The 321LM generates 100 lumens of output and has a tactical runtime of 1.4 hours per battery, with gradually decreasing output afterward. The tough polymer body features a molded-in high-friction pad for enhanced grip in wet or cold conditions. FITS: Mossberg 500 shotgun w/14" Bbl or 6 ¾" forend tube