Properties:

A paper, plastic and/or metal item of square or rectangular shape designed as an aiming point to be used in bore sighting a gun to bring the axis of the barrel of a spotting pistol, spotting rifle, subcaliber rifle and/or telescope sight(s) into coaxial alignment with the center line of a cannon tube or artillery trainer barrel. It usually consists of a series of quartered circles printed on a white background with alternate quadrants printed in black. Crosses, center lines and other appropiate sighting marks may also be included.