Tuff Stuff 90 Polished Brass US3, Keystone Door Viewer. The 90 door interviewer has a 160 degree angle of view, and fits doors from 1/8" to 2 1/8" thick. There is a frame for a number or name on the polished brass finish item. Outside Faceplate: 4-1/8" Tall X 3-1/2" Wide. Used To Allow A User To Identify Visitors From The Security Of A Locked Door.