Child-Adult 300-500ml This is an exercise tool for daily use Recommended for use in the office, Recommended for use at home, Recommended for anyone with free time If you want to improve your breathing quality, you can try buying it If you want to improve your lung discomfort after exercise, you can use it，do daily respiratory Exercise If you want to increase the activity of your chest muscles,you can try using it It does not have therapeutic functions, but using it can improve breathing quality People with health problems are advised to take it step by step and act according to their health situation. Or use before consulting a doctor.