I bought this item because I misplaced my old adapter for the 1st generation iPhone. I expected, as usual, that as soon as I bought a replacement the old one would show up! In this case it didn't. This adapter is used to connect headphones or audio output to the original 1st gen. iPhone. That model had a recessed jack to plug in the headphones and would not accept a standard plug, like the newer iPhones do. Since I am now using the 3rd gen. iPhone, my 1st two are jailbroken to use as iPod Touches, for music, internet and app use. This jack comes in handy when connecting headphones, as the 1st gen. iPhone has a sub-par speaker, and is of little use in listening to music. I would recommend it for anyone still using the original iPhone.