Concept Development Corporation Site-Lite SL-100 Mag Laser Professional Boresighting System. This unique system uses a combination of adapters and o-rings to fit all firearms including .22 to .50 caliber handguns .22 to .50 caliber Rifles 20Ga. & 12Ga. Shotguns and Muzzleloader There are no optional adapters to buy and no metal contacts the rifling. The SL-100 is precision machined aircraft quality anodized aluminum. A system of super strength magnets within the center cone securely holds the SL-100 in the muzzle to insure repeatable superior accuracy. To boresight place the target 25 feet from the muzzle and center the laser spot on the target. Then line up the scope crosshairs with dotted lines on the target and you're boresighted for 100 yards. It's that simple Specifications for Concept Development Corporation Site-Lite SL-100 Mag Laser Boresighting System: Manufacturer: Concept Development Corporation Fabric/Material: Aluminum Package Contents: Concept Development Corporation Site-Lite SL-100 Mag Laser Boresighting System Concept Development Corporation 18001: Site-Lite SL-100 Mag Laser Professional Boresighting System