I do not bother with spec . I use they , they be great . only thing I would change be the long cord . who need 10 foot for a portable mp3 player . but that be easy to solve with a wire tie . the 10 foot do come in handy for listen to my mp3 's on my computer . I have 10 foot to dance around in , instead of the 4 ft. on my older , lower quality sony headphone . so , if you be into spec , I can not help you , but if you just want some great headphone at a great price , these should work for you . they be crisp , but can thump when call upon , too .