This is a Bermuda Round Trip Flight Cover sent from Baltimore to Bermuda.  It has the Return FAM 17 First Flight Marking.  It is a Dual Currency Cover.  It was sent from Baltimore on 3/16/1938, and then from Hamilton on 3/17/1938.  It has receivers from Hamilton 3/16 and Baltimore 3/17 on the back.  This is an absolutely immaculate cover!