USA Table Tennis (USATT) is the national governing body for the Olympic sport of table tennis in the United States. It is affiliated with the International Table Tennis Federation(ITTF). The laws imposed by USATT conform substantially to the International Table Tennis Federation ITTF Laws and Regulations for International Competition.
2.3 The Ball
2.3.1 The ball shall be spherical, with a diameter of 40mm.
2.3.2 The ball shall weigh 2.7g.
2.3.3 The ball shall be made of celluloid or similar plastics material and shall be white or orange, and matt.
USA Table Tennis – http://www.teamusa.org/usa-table-tennis
International Table Tennis Federation – http://ittf.com/_front_page/ittf.asp?category=General
ITTF Laws of Table Tennis – http://www.paddlepalace.com/Manuals/Rules_ITTF.pdf
Photo – chrisreablog.wordpress.com/tag/ping-pong/