Markings under bill are patent #1855527.

See pictures for condition.

Mallard head duck call, Natural Duck Call Co., St. Paul, Minnesota.

With metal bill that opens when blown. Measures 6 5/8" long.

Francis J. Muehlstein maker of the "The Natural Duck Call” was granted a US patent, 1855527, on April 26, 1932. It was Mr. Muehlsteins’ intention to provide a simple and highly efficient duck call where extensive experience and extraordinary skill are not required to produce successful results. Mr. Muehlstein contended that it took skill in manipulating your hand to make a traditional duck call sound good. His new duck call imitated a real duck's vocal system so you wouldn't have to manipulate your hand. The call is a wooden Mallard Drake Head with glass eyes and a hinged metal bill. When you blow through the neck the reed in the head vibrates producing a duck call sound while the hinged bill flaps with the passage of air and sound. (Description taken from Callcollector.com)