Deep Breathing Exerciser for Comprehensive Respiratory Fitness from 600cc/sec to 1200 cc/ sec. The three balls are used to help measure and encourage deep inhalation. As you inhale, the balls rise in the device, providing visual feedback on the volume of air you're inhaling. This can help individuals practice deep breathing. It's designed specifically for lung exercises and breathing improvement. Using a spirometer regularly can help strengthen your respiratory muscles and improve lung function. HOW TO USE: Assemble the spirometer.Sit or stand upright.Inhale through the mouthpiece,raising the three balls. Hold your breath briefly. Exhale slowly, lowering the balls. Repeat the exercise as recommended. Clean the spirometer after each use.