Split your 4-pole TRRS input jack (combined audio jack) into separate jacks one for microphone and one for stereo headphones
This compact adapter allows you to plug your headphones and various types of microphones into your iPhone or similar device that uses 4-pole TRRS connector at the same time. It includes a convenient volume adjuster for your 3.5 mm (1/8 inch) stereo headphones.
Motorola Droids, HTC phones and Apple iPhone, ipod, phone, pod, palm, treo