The dunlop pro squash balls 1 dozen 4 x3 ball tube are high quality balls that are perfect for professional tournament and club use an elastic hydrocarbon polymer is impregnated with 12 compounds resulting in a construction material with supreme playability and durability characteristics they come in 4 tubes of 3 balls and are the official balls of the world squash federation wsf professional squash association psa and womens international squash players association wispa as well