query: What are basketball's made out of?
passage: Basketball (ball)
Nearly all basketballs have an inflatable inner rubber bladder, generally wrapped in layers of fiber and then covered with a surface made either from leather (traditional), rubber, or a synthetic composite. As in most inflatable balls, there is a small opening that allows the pressure to be increased or decreased.
passage: Ball bearing
There are several common designs of ball bearing, each offering various performance trade-offs. They can be made from many different materials, including: stainless steel, chrome steel, and ceramic (silicon nitride (SiN)). A hybrid ball bearing is a bearing with ceramic balls and races of metal.