... 2.Memorizes up to 4 frequencies. 3.Work for iPod FM Transmitter for iPhone3GS& iPhone 4Features:1. High fidelity,Stereo, ... Memorizes up to 4 frequencies5. Draws power from iPhone or iPod,no batteries required6. With charging socket at the bottom7. ... 3G S, iPhone 3G,iPhone,all iPod models(Incl.iPod nano 3rd & 4th generationiPod touch 1st & 2nd generation,iPod classic) For iPhone 4 & iPod FM Transmitter