Giyosk Breathing Exercise Device for Lungs, Lung Expansion and Mucus Relief Device, Portable Expiratory Breathing Exerciser with A Set of Accessories, Breathing Trainer for Lung Cleanse(Green)Brand: Giyosk Color: Green e Features: [Natural Way] Get rid of your mucus with exercise. [Easy Breathing] Just practice 10 to 30 minutes a day. Get easier breathing and better athletic performance. [Easy to Use] This breathing exercise device is lightweight and compact, easy to use anywhere. There are no complicated level settings and incomprehensible accessories, the only thing to consider is which metal ball to choose. Suitable for your long term