The actual prototype of the K-ration was a pocket ration for paratroopers developed by the Subsistence Research Laboratory (SRL) at the request of the U.S. Army Air Forces (USAAF) early in the war [REF].
One major criticism of the K-ration was its caloric and vitamin content, judged as inadequate based on evaluations made during and after World War II of the ration's actual use by Army forces [REF].