Strengthens key muscles in the abdomen, enhances core health, critical for endurance, posture & balance;Place the Mini Ball under your lower back when performing crunches for a more challenging & intense workout;Add an extra dimension of balance or resistance to your workout routine when positioned between your arms or legs or between you & the floor or wall;9 Inch Diameter ball is slightly textured to stay in place when doing Pilates, exercising or during physical therapy;No need for pump, can be inflated with included tube and breath;Tactile, stretchy PVC;Responsive to the touch and non-slip when placed against a hard surface;Instructional poster is included