In most rifle scopes, the hood is the point of aim in your field of vision. Also known as "cross lines", these are glass etched, or most commonly made of wire.
The collimator is produced by a non-amplifying optical device, such as a reflector sight (commonly known as a reflection sight), which provides the observer with a mask image superimposed on the field of view, and a blind collimator sight for both eyes. Produces a collimating mask using a refractive or reflective optical collimator to produce a collimating image of a illumination or reflection mask. These types of attractions are used in surveying/triangulation equipment to help celestial telescopes aim and serve as attractions for guns. Historically, they have been used in larger military weapon systems that could provide power to illuminate them, and operators needed a wide field of vision to visually track and locate moving targets (i.e., weapons from the laser/radar/computer era).