P-51 Can opener is an update of the World War II P-38 can opener for C-rations. At 2" long, the P-51 is easier to use. Key ring attachment hole, folds flat for carrying. (US Govt. #P-51-2-1503.
The P-38 can opener is 1 1/2" long and half the weight of P-51.
In an emergency these small tools can open crates and boxes or tighten scope ring mount screws, but the greatest utility is having a can opener available at all times for emergency use.