The Axeon Second Zero is the fastest way to compensate for bullet drop at extended range. The Second Zero shifts a target image up by the same number of inches a bullet drops over a specified distance. The Axeon Second Zero is a precision optical device that gives any rifle shooter an instant additional zero distance whether in a hunting or tactical application. Its an aiming device used in conjunction with your standard rifle scope. It is a prism driven optical device configured to bend light at a precise minute of angle to achieve an additional zero (second zero) downrange. The device mounts forward of your rifle scope, right over the bell, as long as it does not have an adjustable objective. Your scope functions normally when the Second Zero is not being used. When engaged, the prisms of the Second Zero, shift the image to compensate for bullet drop. Simply place the crosshairs on the target just as you would at 100 yards. You leave your optic sighted in at 100 yards and your Second Zero provides you an additional distance. This unit provides 4.3 MOA or 330 yards as tested with most hunting rounds.