Roof prism is combined with a right angle prism and a totally internally reflecting roof and they are attached by them largest square surfaces. It can invert and reverse an image, also, deflect the image 90° . Therefore, it is often used in terrestrial telescopes, viewing systems and rangefinders.          

Specifications           

Material: BK7 Grade A Optical Glass           
Dimension Tolerance: +0.0, -0.2 mm  
Clear Aperture: >80%   
Angle Tolerance: ± 3arcmin      
Flatness: λ/2 @632.8 nm    
Surface Quality: 60-40 scratch and dig    
Protective Bevel