Feature:
Breathing exercise equipment to challenge yourself for better exercise and improve overall endurance.
Vital capacity - it helps to expand and improve vital capacity without the risk of having to do a lot of aerobic exercise and burning calories.
The portable device - Adventure lung breathing training instrument is very compact. Easy to carry.
The adjustable resistance dial makes the simplest task more difficult, and can exercise more intensely according to your needs.

Specification:
Material: silicone