Sightmark Laser Boresight 12 Gauge #SM39007A quick and easy way to sight in your rifle scope, Sightmark Boresights give you a versatile tool to ensure an accurate aim. Offered in a multitude of in chamber calibers as well as many different universal boresight options, these tools help you sight in a new gun or check the zero on your scope after a turbulent flight or other rough treatement. Quality boresights also make a great training aid when drawing your weapon.