Penta prisms deviate beams by 90 degrees without changing the orientation of the resulting image. The deviation is independent of prism orientation. Due to the geometry, the reflecting surfaces must be coated with a metallic or MAX-R coating. Penta prisms come standard with an protected aluminum coating.

Antireflection coatings are available for entrance and exit faces.

ultiQuest Technology supplies prisms with three levels of deviation tolerance. The standard series has a deviation tolerance of less than 1 arc minutes. The precision series has a deviation tolerance of less than 10 arc seconds or 5 arc seconds more.