Due to construction and functional characteristics above described, with the internal reflux column it is possible to get selective the separation of components of extremely complex mixtures, with similar chemico-physical characteristics, not economically separable otherwise.
Uniform numbers in American football are unusual compared to those in other sports. They are displayed in more locations on the uniform; they are universally worn on both the front and back of the jersey; and in many cases TV numbers are displayed on either the jersey sleeves, the shoulder pad, or occasionally on the helmets.
Helmet: As you would probably suspect, the helmet is the most important piece of equipment in football. Face masks are mandatory, a visor is optional. Jaw pads can also be worn attached to the bottom of the helmet and provide some protection against concussions. Contrary to popular belief, most of the football helmets currently in use do little if anything to protect brains from the forces that cause concussions.