general postal service ( 3. planned trip), with unusually and very rare franking denomination ( twice 2 1 / 2 pfennigs plus 15 pfennigs) provided letter of the 1. weight rate as inner envelope to the USA, submersible stamp from 16.1.17, rare censorship stamp X and large" return" cancel, without reimbursement memo, impeccable and very rare cover, Michel / Geissler approximate 575.-