We recommend replacing your balls every 3-6 months based on use. The Therapy Balls, especially the Original sized balls, will break down and soften with use. This is a good thing as it’s great to have a pair of extra soft balls for soft tissue work directly on small bony areas (such as your wrists, elbow, ankles, and toe joints). It may however be too soft for larger areas where you want deeper pressure, so having a few pair around is all part of filling out the tool box.