I recently purchase a home built in 1937, the door is wood and it has a small iron door that one can open to see who is at the door. I do not know the proper name for this door within a door? The small opening is made of iron or steel with a latch and ornaments and bars on the other side. A small part of the latch to iron door has disappeared, not sure why. I think it's been the movers and contractors over the past 2 months. Does anyone know what this might be and who to contact for restoring this?