This is an Altman Snoot with required mounting frame and holder. It fits the Altman PAR64 Outdoor tungsten light.
Use of a snoot will result in a small circle of light, when it is attached to the front of your light source. The size of the circle of light will be determined by the opening of the snoot, its length, and the distance of the subject. Consider them as a painter would a brush, or a sculptor would a knife, or chisel.