rEICHSMARSCHALL der DEUTSHCHEN REICHES,,ETC

[militarymania]

SIZE IS 6.25 X 5 INCHES,,,RAN ACROSS THIS THE OTHER DAY...WHAT TYPE OF CORRESPONDENCE WOULD BE MAILED IN THIS ENVELOPE?,,,ANY VALUE?...i HAVE NEVER SEEN ONE OF THESE BEFORE. THANKS FOR ALL REPLIES. ROBERT