1.Simple design and easy to use
2.Use to charge and transfer data
3.Connect to a audio cable, play music through a sound box

Technical DetailsEigertec Black Sync Charger Dock Cradle for iPhone 4 4G Audio out CradleProduct Description* Simple design and easy to use * Use to charge and transfer data * Connect to a audio cable and play music through a sound box * Audio interface:3.5mm connector * Compatible with: iPhone 4G Shipping Weight: 4.8 ounces