https://blog.wongcw.com/2019/02/11/airpods-2%e6%9c%89%e7%89%b9%e6%ae%8a%e7%9a%84%e9%98%b2%e6%bb%91%e5%a1%97%e5%b1%a4airpower%e4%bb%8a%e6%98%a5%e7%99%bc%e5%94%ae/