Vector Optics Bore Sighter Features For 243 308WIN 7mm-08REM Caliber, Cartridge Style, Convenient and Accurate, Brass Material Brief Introduction: By project a laser beam from the center of the barrel axis of firearm, this laser bore sight collimator allows you to instantly & accurately set your sight or scope etc. The laser light emitted from the laser bore tool travels in a straight line while the bullet follows a trajectory. Even though the use of this device will get you very close, final adjustment should be made at the range. Power: <5mW Wavelength: 650nM Weight (net): 26g (0.9 ounces) Length: 45.5mm (1.8 inch) High quality brass in durable finish Already set center aligning in factory Package Including: Instruction, laser bore sight, 4 pcs AG3 Battery