This all-black bracelet comes in a thick wrist wrap that has a cable extension to connect to your mobile devices and charge them. New to this model is an adapter cable that will allow you to even pair this up with a greater number of mobile devices. It will also come with a 1,500mAh lithium-ion battery and an on/off switch.
You can get this Thanko bracelet battery for ¥3,980 or about $40.