It's hard to find a belt for Sony Mini Disc players that are comfortable and small enough. Most "fanny pack" style carriers are too big, or are made of nylon, which can chafe. Others are arm band that chafe and slide down in you have skinny Mr. Peanut arms like I do. I like this carrier because it's made of neoprene (wetsuit material) which makes it light, stretchy, and dries quickly. It hides well under your shirt, and has a night reflective logo on the back (but if you're jogging at night with headphones on, you are just asking for trouble). It has enough room for a Mini-Disc player, with one or two extra discs and a spare AA battery. The only design flaw I could see was that there is no hole for the headphone jack; it just sort of jams in there. But since the case is so flexible, it won't ruin the headphone jack. I like running with Mini-Disc players over CD players since they don't skip, and I'm just not down with the whole IPod fad. I recommend this product to any runner who needs music while wheezing and sweating.