I have become a Esterbrook collector inadvertently thru some of the lots I've bought. I know many turn their noses up, but I think that they are fine pens and way under-rated! Anyway long story short this showed up in a recent lot, and now I guess I am into Esterbrook dip pens too. The pen holder is 6 and 3/4 inches long with a nickel plated brass ferrule that says on it length wise ESTERBROOK'S, MAMMOTH FALCON, around one end in a band it also says PAT'D AUG. 21 - 1877. The nib is 2 and 5/16's long, and 7/16's wide. On the nib lengthwise it says 340 Eterbrook & Co's, Mammoth Falcon. Check out the picture next to a "regular" nib and holder.

John-

Love those mammoth falcon nibs. Take a look at some pics I have up on a previous post:

Mammoth Falcon

Do you have the same marking on your holder? Those nibs are as big as a cap.

Best-
Brian