product description:
1> Steel thread hoop, high capacity in expansion
2> Unique clip design at the end of hoop, which could be easy to adjust for comfortable wearing
3> Noise reduction rate: 28db
product description:
1> Steel thread hoop, high capacity in expansion
2> Unique clip design at the end of hoop, which could be easy to adjust for comfortable wearing
3> Noise reduction rate: 28db