The regular dies trial piece. Examples of this design were struck from both the 'Small Motto' and 'Large Motto' obverse dies which probably means that they were struck at different times. The illustration below courtesy of PCGS shows the difference in the size of the motto.
Examples of this design are known as follows:
Copper J370. This was delisted by Pollock as being virtually indistinguishable from a regular bronze piece. At least 2 different examples have been slabbed by the grading services.
Copper-nickel J371/P440 with over a dozen known. Metallurgical analysis is recommended as oddly toned regular proofs could be misattributed as one of these.
One of these is known on a broad 144 grain planchet which has been misdescribed in Judd and Pollock as a J364/P438. It is now listed as J371A. It is ex Brenner-1914 ANS, Pine Tree 9/74 where it is illustrated and shown to have the regular reverse.
Aluminum J372/P442. This is believed unique and is ex Loye Lauder, J.E Drew, Simpson collection - PCGS64.
Nickel J372A/P441 with 2 known. One of these has been described as slightly magnetic and is listed by Pollock as being in the J.E. Drew collection ex B/R 1/75, Hughes 10/80. The other is a well worn example, PCGSVG8, which is in the Simpson collection.
Copper J373. This is unlisted in Pollock. At least 2 different examples have been slabbed by the grading services.
Copper-nickel J374/P436. This is unconfirmed.