Please Help Identify Erco Wooden Propellers 1920s Value

[jtmseller]

Can someone help me identify the value of this propeller? I was told very rare, only at the Smithsonian, ect....I have not been able to google anything close, that resembles this propeller. I do not know what type of plane it came from, and when I aquired it in my Grandmothers estate, there was only the information that had been told through the years.
I was told to have it appraised by a collector.....by my Grandfather long ago.
I am having trouble even identifying it, and I am googled out. I have spent months trying to locate some information. Can anyone help

Serial numbers are on the bases.

[MWP_Lamar]

That is an adjustable prop. I would suggest you contact Monty at his website that deals with adjustable props at www.notplanejane.com.

Lamar