Projects a bright red laser dot so you can set scopes, red dots, or iron sights quickly and easily. Cone-shaped spud and interchangeable inserts automatically center the laser unit in the bore of any .22 to .50 caliber gun with a 4" or longer barrel for standard models and 3" or longer for mini models. Permanently calibrated with precision alignment tooling at the factory; projects a 2" to 3" diameter dot at 100 yards. CNC-machined from aluminum, then hardcoat anodized to protect the finish from nicks, dings, and surface wear. All models provide 1.5 hours continuous use. Automatic digital circuitry adjusts laser output to prevent brightness fade toward the end of battery life. Mini Universal Kit includes the laser unit with a 650-nanometer red laser, integral bore spud, and four inserts to fit any handgun or rifle up to .50 caliber. Uses 3 inexpensive 393 batteries, included.