The dunlop pro are double yellow dot squash balls designed with professional tournament and club players in mind who look for unmatched durability and playability ensured by the n 1sr molecular technology these 40mm competition balls offer the lowest bounce in the range and are supplied as a 1 dozen pack 4 x 3 ball tube they are the official balls of the wsf world squash federation psa professional squash association and wsa womens squash association