Acoustic Amplifier Without Electricity for the iPhone 4

The volume of the internal speaker is not necessarily the "strength" of the iPhone 4, which are likely to know most. But now there is a possibility the iPhone to a helping hand, without electricity or battery.

Talking about the play for AirCurve iPhone 4.

The AirCurve Play by Griffin is an acoustic amplifier, which is unique of its kind in. It was developed by acoustic engineers and works like