ProsourceFit Weighted Toning Exercise Balls for Pilates $8.99 – $15.57 Make sure this fits by entering your model number. BALANCE, STRENGTH & STABILITY TRAINING – Unstable sand filling in these Pilates toning balls force deeper muscle activation engagement during exercises for a stronger and leaner physique VERSATILE UTILITY – Weighted exercise ball is suitable for all fitness levels and ideal for Pilates, strength training, yoga or physical therapy exercises