Similar to the Pollock-4055 pattern cent, this Pollock-Unlisted cent is believed to be from the experimental roller press that General Motors created for the Mint. This piece is simpler than the Pollock-4055 and is therefore thought to predate it. In the 1960s, there was a coin shortage that caused the U.S. Mint to contract General Motors to create a coin press with the capacity of 10,000 per minute. GM developed a small-scale prototype that was promising enough for the Mint to commission a full-scale press. However, although the press worked as planned, the maintenance required to keep the press running was its downfall. The machine had to be shut down to replace cracked dies, the dies were cracking more often due to the speed and the press and its dies required frequent lubrication, and some of the oil leaked onto the metal strips used for coins, causing an undesirable ripple effect. The only lasting evidence of this press are the prototype coins printed in the press, such as this one.