Each Aramith ball is 100% 'cast phenolic resin'. On the break, the cue ball reaches 20 miles per hour in a fraction of a second causing surface temperature to easily reach 482 degrees Fahrenheit! Aramith's molecular structure is engineered to withstand these temperatures making Aramith balls far less vulnerable to burn spots, resulting in minimal ball and table cloth wear. Numbers are printed in the field Set includes 8 solid colored and 7 crown striped balls and 1 cue ball