Features: -It works your breathing and strengthens your abdominal muscles, which increases lung capacity, helping you improve your exercise endurance and overall performance. -Its resistance is adjustable by rotating the valve to meet different exercise needs. -Small size, light weight, easy to carry, can be used anytime and anywhere. -Made of silicone and ABS, it is wear-resistant, tear-resistant and has a long service life. -Suitable for athletes, singers, smokers, people with lung diseases, etc. Specification: Colour: black&white Material: silicone+ABS Size: 5*10cm Package Included: 2x Breathing trainers .
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