Kneass's draped Liberty design combined with Gobrecht's standing eagle. A sketch for the standing eagle reverse is available for viewing by clicking here.
Supposedly, these exist as both originals and restrikes. Originals should have been struck from unrusted dies, weigh 206 grains and have 143 reeds around the edge. Restrikes were made throughout the 1840s possibly into the early 1870s. As these dies were used over a long period of time, specimens show varying degrees of repolishing and/or die rust. Those made after 1853 should weigh 192 grains. Reed counts may vary on these and thus could possibly be used to determine what year a given piece was struck. The fact that the original Mint collection does not contain an example may also be significant as this pattern would have been produced at the initial formation of the collection and likely would have been included if it was actually struck in 1838.
Overall there are probably 50-60 known. Virtually all were struck in medal alignment.
There is also a listing for this design in copper in Pollock as P76 that was taken from Taxay's Comprehensive Encyclopedia where it is listed as EP95. It is said to be ex A.M. Smith but I did not notice it in any of the Bolender sales which included coins from his collection. Should an example actually exist, it is likely to be a later restrike.
Photo courtesy of PCGS.