Blue Seal © 1931 Watling Mfg. Co.
Nickel Play. Twin Jack Pot
Style 70
Selling price by years :
1931 - $70
1932 - $70
1933 - $59
1934 - $55
Also released as a Dime Play model called "Blue Seal [Twin Jack Pot] [Style 80]", and a Quarter Play model called "Blue Seal [Twin Jack Pot] [Style 90]".
Collector's Treasury of Antique Slot Machines from Contemporary Advertising - Peter Bach - Page 63, 68, 83 & 122
Loose Change Blue Book for Slot Machines [4th Edition]