Hang your Aqua Training Bag before filling. First remove plug with a #2 screw driver, or a penny. Ensure that the plug is removed from the hole. At times the rubber part may get stuck within your Aqua Training Bag. If it does, be sure to remove it, and then reconnect it to the hard piece of the plug. Connect the filling nozzle to hose. Begin filling with, and fill to desired hardness/softness of Aqua Training Bag. If you have filled to your desired amount and there are “wrinkles” top it off with air. You can do this with an inflation needle that pumps up a soccer ball or football, all with keeping the plug inside your Aqua Training Bag. Our black plugs can accommodate the inflation needles. Visit our YouTube channel to see a video on how to fill your Aqua Training Bag: How to Fill your Aqua Training Bag