The P-51 can opener is the larger cousin to the P-38 "John Wayne" can opener. This is an authentic stainless steel reproduction of the US Army can opener that was issued from WWII through the 1980s. It is 2" long.
While the origin of the P-38 and P-51 can openers is unknown, they are said to be named after the P-38 and P-51 Mustang Fighter planes. The can openers are coincidentally also roughly 38mm and 51mm long.