What is the equipment in American Football?
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) (Rule 2); Short circumference: 21 to 21.25 inches (53.3–54 cm) (Rule 2); Long circumference: 28 to 28.5 inches...
Source: NFL — Official Playing Rules of the National Football League — Rule 2, Rule 5