Verdict

The official NFL football (the "Duke") is made of cowhide leather with a pebble-grain texture. It must conform to the following specifications: Long axis: 11 to 11.25 inches (28–28.6 cm); Short circumference: 21 to 21.25 inches (53.3–54 cm); Long circumference: 28 to 28.5 inches (71.1–72.4 cm)