50 Kopeck control mark with dark reddish-purple typography imprint "GK. Ssarny" Type II and Type VIII in a vertical pair, sheet block 20 and 25, cancelled with stamp "BERESCHINZA ROB. OBL. BERESCHINZA -6 11 41" on an unmarked Soviet envelope, condition of the stamps flawless, envelope slightly bumped corners, unsigned, expertise Robert Brunel VP (2025), Michel 800.- +