Roof prisms are also called “right angle roof prisms”or “Amici prisms”. In passing through the prism, the image is both deflected top-to-bottom and right-to-left. The hypotenuse of the prism utilizes total internal reflection (TIR) to reflect the image through the prism.Yutai's roof prisms are made of H-K9L(BK7) or fused silica, other optical glass is available.Yutai Optics' prisms are widely used in Binoculars,Spotting Scopes,Prism Diagonals in an Optical System,Optical Tooling.