Oncourt Offcourt Training Spots 10" (Set of 6) Tennis Training Aids : The OnCourt OffCourt Training Spots 10" (Set of 6) are designed to help plan and execute footwork drills or mark off sections of a field or court for practice. These Spots are designed with a specific weight, a 10" diamter, and anti-slip and dirt-resistant qualities. Praised as the most durable in the tennis industry. Comes in a set of 6 (2 Red, 2 Green, and 2 Yellow).