Bula Balls original dynamic duo are the perfect pair to kick-start your exploration into self-care, self-treatment and self-discovery! While the 7” inch self-myofascial release BulaBall is more perfectly suited for hydrating, mobilizing and stretching the pelvic girdle lumbar spine area of the body to resolve lower back pain, the smaller 5” inch self-myofascial release BulaBall is able to penetrate deeper into the larger muscle and fascial structures of the lower torso. Offering more advancement in fascial elasticity and suppleness to the larger muscle structures, particularly to the over dominate psoas muscles.