Inflatable Bladder

• The inner linings of rubber basketballs are typically made from natural rubber, butyl rubber or a combination of both. The rubber is cut into sheets and bonded together to form a spherically-shaped bladder that can be inflated with air to a specified circumference and volume. Although its use is less common, some bladders are made from thermoplastic polyurethane (TPU). All of these materials have good tensile properties and strong elasticity.
  
  

Cover

• Rubber basketball covers are made from a blend of natural and butyl rubber. The rubber is cut into sheets, dyed a specific color and bonded together to form an outer covering for the bladder. The surface of the cover is usually designed with small, raised rubber dots which give it a "pebbled" look and feel. Rubber basketballs often have a team logo or brand stamped on the cover.
  
  

Winding

• The winding is a gridwork of nylon and/or polyester string that is wrapped tightly around a ball's bladder. A heat-cured adhesive is applied to the bladder to keep the winding in place. That's why if you peel back the cover of a rubber basketball you'll see what appears to be a ball of string or thin yarn.This winding is used to strengthen and reinforce the bladder's shape.
  
  

Air Valve

• Air valves are thin, cylindrical devices made either of metal or rubber that are molded and attached to the ball's bladder. They protrude through the surface of the ball's cover and contain a small opening in which the needle of an air pump can be inserted to inflate the bladder. The opening of the air valve is embedded flush with the surface of the cover.