Issue link: http://itf.uberflip.com/i/428396
20 APPENDIX I THE BALL For all measurements in Appendix I, SI units shall take precedence. a. The ball shall have a uniform outer surface consisting of a fabric cover except for the Stage 3 (Red) foam ball. If there are any seams they shall be stitchless. b. The ball shall conform to one of types specified in the table immediately below or in the table under paragraph (d). TYPE 1 (FAST) TYPE 2 (MEDIUM) 1 TYPE 3 (SLOW) 2 HIGH ALTITUDE 3 MASS (WEIGHT) 56.0-59.4 grams (1.975-2.095 ounces) 56.0-59.4 grams (1.975-2.095 ounces) 56.0-59.4 grams (1.975-2.095 ounces) 56.0-59.4 grams (1.975-2.095 ounces) SIZE 6.54-6.86 cm (2.57-2.70 inches) 6.54-6.86 cm (2.57-2.70 inches) 7.00-7.30 cm (2.76-2.87 inches) 6.54-6.86 cm (2.57-2.70 inches) REBOUND 135-147 cm (53-58 inches) 135-147 cm (53-58 inches) 135-147 cm (53-58 inches) 122-135 cm (48-53 inches) FORWARD DEFORMATION 4 0.50-0.60 cm (0.197-0.236 inches) 0.56-0.74 cm (0.220-0.291 inches) 0.56-0.74 cm (0.220-0.291 inches) 0.56-0.74 cm (0.220-0.291 inches) RETURN DEFORMATION 4 0.67-0.91 cm (0.264-0.358 inches) 0.80-1.08 cm (0.315-0.425 inches) 0.80-1.08 cm (0.315-0.425 inches) 0.80-1.08 cm (0.315-0.425 inches) COLOUR White or Yellow White or Yellow White or Yellow White or Yellow Notes: 1 This ball type may be pressurised or pressureless. The pressureless ball shall have an internal pressure that is no greater than 7 kPa (1 psi) and may be used for high altitude play above 1,219 m (4,000 feet) above sea level and shall have been acclimatised for 60 days or more at the altitude of the specific tournament. 2 This ball type is also recommended for high altitude play on any court surface type above 1,219 m (4,000 feet) above sea level. 3 This ball type is pressurised and is specified for high altitude play above 1,219 m (4,000 feet) above sea level only. 4 The deformation shall be the average of a single reading along each of three perpendicular axes. No two individual readings shall differ by more than 0.08 cm (0.031 inches). c. In addition, all ball types specified under paragraph (b) shall conform to the requirements for durability as shown in the following table: Notes: 1 The largest permissible change in the specified properties resulting from the durability test described in the current edition of ITF Approved Tennis Balls, Classified Surfaces & Recognised Courts. The durability test uses laboratory equipment to simulate the effects of nine games of play. MASS (WEIGHT) REBOUND FORWARD DEFORMATION RETURN DEFORMATION MAXIMUM CHANGE 1 0.4 grams (0.014 ounces) 4.0 cm (1.6 inches) 0.08 cm (0.031 inches) 0.10 cm (0.039 inches)