The Magnus massage ball measures 3.5 inches in diameter and is soft. It is about the size of a softball. Healthy living through self-massage. Using patience and gentle pressure these delightful little massage balls made of soft rubber can ease their way into the soft tissue of the body. Breaking up adhesions and helping tight or tense muscles to let go, the Rollit Therapy Balls are a must-have for anyone interested in self-care. Great for deep tissue work and for myofacial release. Each pair comes with a booklet to help get you started. It contains a few ideas of where you can roll out the soft tissue and how to go about it.