Ferum 902PBR 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 plated item. The 90 VK door interviewer offers a 160 degree view, has a name or number frame, and is polished brass plated. The door interviewer fits doors from 1 3/8" to 2 1/8" thick, and has frame for name or apartment number. 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.