The Exercise Ball Pump can be used to inflate as well as deflate your exercise ball (gym ball) to the required level. It consists of a foot pump, tube as well as fitting pin.
Take the pointed end from your gym ball pump and place it into the hole in your exercise ball. There may also be an adapter that fits over the nozzle of the pump.
This will usually look like a cylinder or cone that comes with your exercise ball. If you have one, simply screw it onto the nozzle of your pump.