Self-study treasure

[suitable for crowd] : children, adults.
[detailed description] : on the basis of last year's experience of the second generation, the processing technology, printing, thickness, color and other important factors have been changed. The third generation of self-taught treasure is softer and more comfortable and durable. The use of self-learning treasure can effectively improve the learning efficiency of beginners' swimming, and enable people who can't swim to experience the pleasure of swimming for the first time, and also improve their interest in learning swimming. It's really a good thing to learn to swim.
Improved upgrade features:
 1. Double air bag design, the head adds an airbag, the security is greatly enhanced, and more comfortable;
 2. Material upgrade, change to elastic material, more affinity to skin, feel soft and comfortable;
 3. Color upgrade to matte, more upscale, enhance visual effect.