Post flap for pigeon holes is mounted on lockable door and is fitted on inside with two swiveling strips of rubber or plastic with interlocking saw-tooth profiles which allow post to be inserted but not removed through flap

摘要

The post flap (3) for pigeon holes is mounted on a lockable door and is fitted on the inside with two swiveling strips (10) of rubber or plastic. These have interlocking saw-tooth profiles and allow post to be inserted through the flap but not to be removed without unlocking the door.