I am a dance teacher and fitness instructor and this using this doc in conjunction with the apple ipod remote has made teaching my classes much easier. It comes with adaptors so it can be used easily with a variety of ipods and is a very useful size that it fits into my overflowing bag with great ease. It has two sockets at the back, one for the device to be connected to a stereo and one to enable you to charge the ipod (something which I find very useful as the battery on the ipod does not last anywhere near long enough for my liking). I have not compared it to other models on the market but as I now have a number of ipods on the go the adaptors (which are ridiculously easy to use) were the main selling point for me. Th remote is also great for the continuity of your class as it means you do not spend most of the lesson running too and from the stereo (something which is priceless when trying to control a room of budding ballerinas!) I lost mine just before xmas and didn't think twice about buying another to replace it.