Differentiation of wire is the reticle, plate is fixed on the sleeve of wire drawing aiming point. The glass plate differentiation is direct line of sight on center of the lens. The glass mirror mostly because the differentiation of metal wire can't make a mark. Such as military aim of digital calibration do glass differentiation. It is for this kind of complex differentiation are generally used in the military aim on the mirror, so can give a person the one-sided sense plate differentiation factors make the grave to extent and ignores the more main effects of craft, such as: the reticle dog at all is wire such as differentiation, not for any reason and aim a graticule is made of glass.