PLAYERS SECTION VII - PLAYER RESPONSIBILITIES/ON-COURT RULES AND PROCEDURES (c) Hardness and Maximum Number The hardness of any pimple or stud is between fifty-five (55) and  sixty (60) based on a shore “A” scale. The number of pimples  per square inch is no less than fifteen (15) and no more than  twenty-eight (28). No pimples or studs may be visible when the shoe is placed  on a flat horizontal surface and viewed vertically. The foxing/ side wall can be contoured only in the medial forefoot and  medial toe area but only within the following restrictions: the  contoured area may begin in the transition area between the  outsole and the sidewall but can only extend to a maximum  of 1.5 cm up the sidewall as measured from the base of the  outsold; and the contoured area must be smooth (not textured  or undulating) but can be stepped with no more than five (5)  steps, each no more than 1 mm in depth. Forefoot and heel areas may be separated, but there should be  no more than a 2 mm step in the outsole of the shoe. As an alternative to the above specifications, players may use  the special grass court shoes developed, tested, and approved  by Wimbledon. Players desiring approval of special grass court  shoes for WTA Tournaments must submit a sample shoe to the  WTA at least ninety (90) days in advance of the grass court WTA  Tournament at which they seek to wear such shoes. In Tournaments played on clay courts, players must wear tennis  shoes generally accepted for play on clay courts or granular surfaces.  The Supervisor has the authority to determine that a tennis shoe sole  does not conform to such customs and standards and may prohibit  its use at any WTA Tournament. Grass court shoes may not be worn during a match on a clay court. ii.  Clay Court Shoes iii.  Hard Court Shoes In Tournaments played on hard courts, players’ shoes must not cause  damage to the court other than what is expected during the normal  course of a match or practice. Damage to a court may be considered  as physical or visible, which may include a shoe that leaves a mark  beyond what is considered acceptable. The Supervisor has the  131