With MFI certificate; With APP Function, IPHONE 4s/4, IPHONE 3GS, IPHONE 3G Touch1-4; Connect the product to IPHONE or IPAD directly, External power supply is not needed; Easy to handle; Suitable for car audio or home audio; App Store free APP software download and install; Passed TDMA test, high SNR, sound good; Button wheel with 3 preset frequency point; Full Band Hi-Fi stereo transmitter; Plug and play, convenient to use