High-quality materialBreathing lung expander Made of high-quality silicone material, non-toxic, no odor, harmless and environmentally protection, you can use it with confidence. High quality Improve durability of breathing and shortness of breath, and provide 100% adjustable resistance for inhalation and exhalation. Easy to use Our lung exerciser device are durable and easy to use. It fits all mouth shapes, can be sealed perfectly, comfortable to use. Versatile, easy to use: suitable for many occasions such as swimming, diving, surfing, running, fitness, travel, etc. Our products are durable and easy to use. It fits all mouth shapes, can be sealed perfectly and is convenient to use.