Yellow metal case with SS back. Inside back marked, "Bulova","10k rolled gold plate bezel","Stainless Back", "New York". Back marked with "Bulova" and "L1" beneath. Also has the serial Number. So as with others on this site I have a 1951 case with a 1953 movement. Radium dial and hands. Appears to be a "Duo Wind"..... It is in great shape and was serviced 2 years ago. Runs quite well. I took off the crappy replacement expansion band that was on it. Will be getting a nice leather replacement.
Case Serial No.