Can be used as teaching tools or research and decoration , they are very beautiful Optical Glass RGB Prism , there are four lights , in of the lighting inputs of the lighting surface , from the three remaining lights , three basic colours red , green and blue , respectively , are said three bases of the light It ' s lightweight And that is , three red , green and blue lights , respectively the base light , of the remaining surface emitting , which is the light Specification : optical glass Size : 20 mm x 20 mm x 2 mm Package includes : 1 x RGB prism optical glass prism It is of the most important accessories on the projector , the projector is capable of projecting color shadows on the screen , you need to know which color of light is composed of three primary colors on the screen , an important color Prism colors, Manufacturer: Watreketal