ProBody Pilates Ball Exercise Ball for Stability, Therapy Ball Workout Ball or Birthing Ball for Pregnancy (Mist, 55 cm)

I am using these balls similar to the ones at an orthopedic therapy center, those were thicker and heavier, but these are of good quality for the price and they do exactly what I wanted to do in duplicating the exercises that I did during the orthopedic therapy for eight weeks. Without continuing a regular exercise program at home, your flexibility and durability in your back will only last 14 to 16 months. Just in case you were planning on not continuing the exercises, that's what you can expect !!