The regular dies trial piece.
Examples were struck as follows:
Copper J668 This is unlisted in Pollock. If any do exist, they are probably masquerading as a regular issue proof.
Copper-Nickel J669/P745 with about a half dozen known. These are likely mint errors as one example is known doublestruck with the second strike 95% off-center, implying the use of a feeder mechanism in striking of them. To view this piece, click, here. Another in Morgenthau's 5/35 sale is listed as being struck without collar, ie broadstruck.
Nickel J670/P746 with only 3 or 4 believed to exist.
Aluminum J671/P747 with fewer than half a dozen examples are believed to exist. These were deliberately struck for sale to collectors as part of complete off-metal sets.
Photo courtesy of Heritage.