Induction Speakers (USA Link) - http://amzn.to/2e84joE
Induction Speakers (International) - http://geni.us/dhsP8
This video features an odd gadget. This little hollow feeling speaker uses induction technology to amplify the speaker of any device you place on top of it. It's actually quite surprising to hear the increase in volume in the absence of a bluetooth or wifi connection to the speaker directly. Is the quality as good as a high-end bluetooth speaker? Not quite, but this thing could still be quite useful given the right application.
Source
Wow, this looks like a good speaker for people who want to save battery life by not using Bluetooth or Wi-Fi for transmitting the sound signal to a wireless speaker.
But, I feel a wired 3.5 mm speaker would be a better choice because it is simpler, and cheaper. The sound may also be better when the sound is coming from a 3.5 mm jack.
Plus, a wired speaker allows you to move the phone around depending on how long the audio cable is.