The penta is a five-sided prism. It reflects light rays through a 90° angle by two reflections and does not invert or revert the image. The reflecting surfaces are aluminized. Slight movement of the prism does not affect the true right angle at which light rays are reflected. It also shortens the optical path length of an instrument.
Commercial Grade Penta Prisms offer commercial quality, at an affordable price. Commercial grade optics have standard designs and are available on an ongoing basis. They are recommended for volume buyers or OEMs.