Does anybody know what this is?

My friend had this cord, and we aren't sure what it goes to. It's Apple branded on the back, and it has play, pause, skip and volume controls, so I assume it's to an iPod, but the plug has this small flat prong to it, and I've never seen an iPod like that. On the top of the bigger box is a headphone jack, so it's almost like it goes between headphones and an iPod, but again, I've never seen an Apple product with in input like that. Thanks for any insight.