The NcSTAR .223 Cartidge Red Laser Bore Sighter fits .223 REM and 5.56 NATO firearms (AR15, M4, and M16). It is a 635-655 nm Class IIIA red laser with a max output of less than 5mw. This laser bore sighter is easy to use. Install the batteries and screw on the base to turn the laser on. Remove the batteries to turn the laser off. The factory pre-aligned cartridge bore sighter hels with zeroing in your optics. It features a brass construction and includes batteries. Fits .223 Remington Chambers Factory zeroed laser Drop into chamber to boresight Projects laser through barrel for fast zeroing Brass construction Batteries included