P-38 can opener

(Not to be confused with the Walther P38, a Nazi German pistol.)

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 2013, it is still in production and sold on a worldwide market.

Role in Fury
In the script, Don Collier was said to have a "GI Can Opener" which he used to scratch notches in his blade every time he made a kill with it. Norman Ellison also was shown using one in the script. A can opener is not seen in the film.