This is a Amplifier shell Specifies for iPhone. It is a fully mechanical amplifier, no power, It simply directs the better the sound of the instrument.
I bought thinking of using in one of my phones, but apparently only fit even on iPhone. What the hell!
You put the iPhone at the top and the sound comes out underneath. It also serves as a vertical support.
See the back. Completely made of silicone.
I don't quite understand this hole on the back.
I don't know if it works well, but the principle is pretty basic. Too bad I don't have found some generic fit in any cell phone. I'll end up buying an iPhone just to test these produtps! I leave the link: