Bulova 1931 Bertram
Nothing on outside case back except "OPEN"
Inside case back: Bulova Quality Pat. Jan. 11 1927 1127945
Single hinge case w/ dust cover intact.
Movement 21 Jewel 6 adjustments Bulova Watch Co.
Dial stamped Swiss
Bracelet: Hallmarked "Sternite"
Case Deminsions: 26.7mm (not counting crown) by 36.4mm lug tip to tip
Crystal: 15.6mm by 21.4mm measured in case at bezel/crystal edge
First digit of case serial number used to determine production date.