Made of BK-7 optical glass. Length & width are 30mm, and hypotenuse is 42mm. Right angle prisms are used to achieve a 90 degree light path bend. The image will be erect and reverse left to right. Can also be used in combination for image/beam displacement. These are unused and have surface quality of 60-40, dimensional tolerance of +- 0.2 arc min, angle and pyramid tolerance of +- 3 arc mins, and surface flatness of about 1/2 wave.