P-38 can opener

The P-38, developed in 1942, is a small can opener that was issued in the canned field rations of the United States Armed Forces from World War II to the 1980s. Originally designed for and distributed in the K-ration, it was later included in the C-ration. As of 2017, it is still in production and sold on a worldwide market.

The P-38 is known as a "John Wayne" by the United States Marine Corps, either because of its toughness and dependability, or because of an unsubstantiated story that the actor had been shown in an as-yet-unidentified training film opening a can of K-Rations. The can opener is pocket-sized, approximately 1.5 inches (38 mm) long, and consists of a short metal blade that serves as a handle, with a small, hinged metal tooth that folds out to pierce the can lid. A notch just under the hinge point keeps the opener hooked around the rim of the can as the device is "walked" around to cut the lid out. A larger version called the P-51 is somewhat easier to operate. The handle portion can also double as a makeshift flat-blade screwdriver, with limited ability because of the rather soft sheet metal used.

Official military designations for the P-38 include "US ARMY POCKET CAN OPENER" and "OPENER, CAN, HAND, FOLDING, TYPE I". As with some other military terms, e.g., "jeep", the origin of the term is not known with certainty; the P-38 opener coincidentally shares a designation with the Lockheed P-38 Lightning fighter plane, which could allude to its fast performance. The P-51 can opener, while larger and easier to use than the P-38 can opener, also has a fighter plane namesake in the North American P-51 Mustang. One technical explanation for the origin of the name is that the P-38 is approximately 38 millimetres long. This explanation also holds for the P-51, which measures approximately 51 mm (2.0 in) in length. However, use of the metric system in the US was not widespread at this point, and United States Army sources indicate that the origin of the name is rooted in the 38 punctures around the circumference of a C-ration can required for opening.

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