The Holocaust Historiography Project
Auschwitz, by J.-C. Pressac
Photo 34 Photo 34:

Outside of PMO II-5 64/2, of the second pattern, door 40 by 50 cm. in excellent condition.

Photo 35 Photo 36
Photo 35:

and …
Photo 36:

PMO II-5-64/2 with its “door” open.

In order to make it gas-tight, two bands of felt were nailed to the door and the frame (strips of felt can still be seen on the frame).