1942 Formula Letter From Sachsenhausen Concentration Camp

1942 formula letter from Sachsenhausen Concentration Camp. The letter is a folding card with instructions (see photo) to the sender and a space for a message. Sachsenhausen, in Oranienburg Germany, near Berlin, was a brutal camp, noted for extermination of Russian POW's as well as political and religious prisoners. Content mail censor office B. Uses Leipzig 12pf stamp, probably sent to inmate by family. Small closed tear bottom, otherwise overall excellent shape considering conditions this survived.