Triad Ball Exercise Ball by Ball Dynamics. Save 54 Off!. $19.19. The Triad Exercise Ball was developed by Pilates Master Trainers Michael Fritzke and Ton Voogt to deepen your Pilates workout. The Triad Ball is slightly larger than a mini exercise ball, and it helps you get the benefits of an expensive Pilates studio workout in the comfort of our own home. Not into Pilates? Use the Triad Ball when doing sit-ups to build core strength.