Roof Penta Prisms are size-sided reflective-type prisms which are used to deviate light by a constant 90-deg. The reflections inside the roof penta prisms are not due to total internal reflection but due to the reflective coatings on three surfaces. The two adjacent transmitting surfaces (with right angled) can be AR coated upon customers' request. The light entering into the prism reflects inside the prism 3-time allowing the transmission of an image through a right angle without inverting or reversing it. Pair of this roof penta prism are typically used for integration of mobile periscope system.