This is a very cool handset for your iPhone 4 3G S which eliminates over 99% of cellphone radiation. Compatible with all 3.5mm jack mobile phones and computers, including iPhone, BlackBerry, iPad, and the latest MacBooks.

Specifications:

Frequency: 20~20000 Hz
Sensitivity  : 111dB + /- 3%
Impedance: 150 ohm
Speaker diameter: 38mm
Retractable Cable Length: about 2m
Connector: Φ3.5 mm
Weight: 215g
Colors: Red, black, pink, yellow, white