Absolute beauties. Consists of 3 BK7 optical glass right angle prisms cemented with Norton UV Optical cement in such a way as to invert and revert the image so the image is correct. in your optical instrument. Prism assembly is 90mm long by 55mm wide. Faces are 55mm x 34mm for a nice wide field. All surfaces are flat within 1/2 wave and coated with multilayer broadband anti-reflection coating with wavelength range of 425-675nm. Transmission is optimized for 0 degree angle of incidence. Included enclosure is made of black ABS. Great for all kinds of optical instruments including large binoculars, telescopes, etc. Prism assembly weighs 1 pound. A rare find. Unused.