50 Pfg grey, 1 Mark rose lilac two single stamps postage stamps issue smelting works and peace pigeon 1920 on registered letter from Katowice to Berlin, ZKr Katowice 20.3.1921 (141.20) as well additional cancellation black rectangle cancel with two lines "from the postbox", the additional cancellation implied, that the registered and / or special delivery cover, contrary to the regulations, from sender not at the post-office counter delivered was but rather within a mailbox found was, consequently the postal administration no responsibility for possible delays at the delivery takes over and all referring to this rejects claims for damages, this secondary postmark is very rare, there are only a few examples known, the here offered letter was in the Table in the OS handbook under the running number 13 documented, arrival postmark ZKr Berlin Weissensee 21.3.1921 at back, transport traces