The Rio500 is a great MP3 player - in this reviewer's opinion, the best on the market currently.  Its size (smaller than a pack of cigarettes) and weight (about an oz.) recommend it to shirt-pocket musicophiles and,  especially, athletes! (You can jog all day with nary a skip, and with the  included netting belt-clip, it will definitely NOT pull your jogging shorts  down, weighing about the same as a pager.)