LaserMax CenterFire Laser for S&W J-Frame-G (For Models 642,442, 637, 638 & 438) Centerfire j-frame mounted green laser with constant or pulsing beam( for Smith models 642,442,637,638 and 438) Custom designed to fit Smith and Wesson j-frame Mounts to the frame without changing out parts or altering your weapon Sits just under the bore for highest accuracy and prevents your finger from blocking the beam Controlled Activation offers distinct on/off switch that turns the laser on only when you need it Class IIIA laser, &lt;5mW power output Type: Gun Laser Ambidextrous activation for right and left-handed shooters Green laser