Rockwood 622.Brs - Bright Brass Finish - Brass Material - 190° Door Viewer - Door Thickness 1-3/8". Door Viewers Also Called Peepholes Which Consist Of A Lens And Cylinder Which Is Inserted Into A Door Allowing A View Outside. The Amount Of Visibility Is Determined By The Degree Of The Lens The Higher The Number The Greater The Visibility. Door Viewers Are Sometimes Incorporated With Door Knockers.