Although similar in appearance to the production design of 1875, these are actually patterns from different dies. The obverse on these shows Liberty incused on the shield as opposed to raised as on the regular die. The reverse is also similar to the regular issue of the following year but with the following differences. The second arrowhead points well above the "T" in "Twenty" and all 3 leaves point toward the eagle's wing. On the regular die, the second arrow points to the tip of the "T" and the bottom leaf points to the "T" in "Cents".
Examples were also struck as follows:
Silver J1411/P1554 with over a dozen known.
Copper J1412/P1555 with over a dozen known.
Aluminum J1413/P1556 with fewer than a half dozen known.
Photo courtesy of Heritage.