Exercise Ball Base - Black Keep your exercise ball stable for various exercise and physical therapy routines Sturdy, one-piece design with no assembly required Put an exercise ball (sold seperately) on the base to use as a chair or seat Slots on the base allow for bands and tubing (sold separately) to be added to the base for additional exercises Works well with 65cm (25 inch) dimaeter and 75cm (30 inch) diameter exercise balls